Category: Baseball 2011

Part II here.
Who are the best defensive teams of all time? Individual defensive statistics in baseball – as in other team sports – have been crudely kept and poorly understood for years, with the more sophisticated modern methods only being gathered for the past decade or two. As a result, even statistically-oriented baseball fans have tended to answer questions about defense as much by reputation and anecdote as anything. The lack of a statistical framework tends to make defense a bit invisible in our memories; even most knowledgeable fans have no more concrete sense of, say, Ty Cobb as a defensive player than they do of Turkey Stearnes as a hitter. My goal in this essay is to a little bit to remedy that on the team level.
We do have one measurement of team defense that endures over time and thus can be used as a baseline for measuring team defense: Defensive Efficiency Rating (DER). I’d like to walk you through the history of the best and worst teams in each league, and the league average, in DER from the dawn of organized league ball in 1871 down to this season. As usual, I’ll try to explain here what I’m measuring in terms that make sense to readers who may not be all that familiar with the ‘sabermetric’ literature, although I make no claim to be current myself on every study out there, and welcome comments pointing to additional studies.
What is DER?
DER is, put simply, the percentage of balls in play against a team that are turned into outs. The exact formulas used to compute DER can vary a bit, and while Baseball-Reference.com – which I used for this study – computes DERs all the way back to the start of organized baseball in 1871, its description of the formula is a bit vague:

Percentage of balls in play converted into outs
This is an estimate based on team defensive and pitching stats.
We utilize two estimates of plays made.
One using innings pitched, strikeouts, double plays and outfield assists.
And the other with batters faced, strikeouts, hits allowed, walks allowed, hbp, and .71*errors committed (avg percent of errors that result in an ROE)
Total plays available are plays made + hits allowed – home runs + error committed estimate.

All methods for computing DER look at the percentage of balls in play that become hits; it appears that Baseball-Reference.com’s formula also counts the outs that result from double plays or outfield assists, both clear examples of outs created by good defense, as well as counting against the defense the one thing that fielding percentages always recorded – errors – but only where they put a man on base. From what I can tell, essentially the same formula is used over all of the site’s historical DER data, so the data is generally consistent over time.
It’s worth recalling that DER only measures outs vs. men reaching base – it doesn’t deal with extra bases on doubles and triples, or stolen bases and caught stealing, or other baserunning issues. So, it’s only one part of the picture just as on base percentage is just one part of the offensive picture. But like OBP, it’s the single most important part.
What Goes Into Team DER?
One of Bill James’ maxims throughout the 1980s was that “much of what we perceive to be pitching is in fact defense.” As most of my readers will recall, Voros McCracken broke major ground in the field of baseball analysis of pitching and defense in 2001 with a study showing that Major League pitchers, over time, had no effect – or at least, there was no difference among Major League pitchers in the effect they had – on whether balls in play become outs. Strikeouts, walks and home runs (the so-called “Three True Outcomes”) are the pitcher vs. the hitter, mano a mano, but on average, BABIP (batting average on balls in play, the flip side of DER) shows no tendency to be consistent year to year among individual pitchers; other statistical indicators also strongly suggest that a pitcher’s BABIP tends to be mostly a combination of team defense and luck. The simple way of expressing McCracken’s insight is that it’s the defense rather than the pitcher that determines how many balls in play become outs.
As with most groundbreaking insights, further research has added some caveats to McCracken’s theory. The first one, which he observed from the beginning, was that knuckleballers tend as a group to have lower than average BABIP, and thus are something of an exception to the rule. I haven’t absorbed all the further studies, but there are reasons to suspect that other classes of pitchers may have a modest advantage in the battle against BABIP, including elite relievers (Troy Percival, Armando Benitez, Mariano Rivera, Trevor Hoffman and Keith Foulke all seemed to have much lower career BABIP than their circumstances would suggest) and possibly pitchers who throw a huge number of breaking balls (we’ll discuss Andy Messersmith a bit below).
Also, McCracken’s research, and most of the following research, looked at the conditions of modern baseball (at the time, Retrosheet and Baseball Prospectus’ database only went back to the mid-1950s). It’s entirely possible that pitchers had greater influence on BABIP/DER in the era before 1920, or further back, when there were pitchers who had consistent success even in the era when most plate appearances resulted in a ball in play and thus the pitcher had little opportunity to set himself apart from his peers by success in the Three True Outcomes. As I explained in this 2001 essay, the playing conditions were greatly different in 19th century baseball in particular, and I’d be hesitant without data on that era to just assume that the pitcher’s effect on balls in play was as minimal then as it is now.
Finally, of course, as with other statistical measures, there are park effects. We all know that different parks are more or less favorable for hitters, and of the components of that, park effects on home runs are significant, and parks can effect walks and strikeouts as well. (Less so for baserunning, in most cases). Balls in play are no exception, and I don’t have data handy on how park effects specifically affect balls in play over time besides the ability to notice some trends (for example, the Polo Grounds for many years was a great home run park but not a great hitters’ park; I assume DER there tended to be high) and a few specific examples where I dug into the numbers we have. So bear in mind that the numbers set out below are not park-adjusted.
Key to the Charts
BIP%: Percentage of plate appearances resulting in a ball in play (i.e.,Plate Appearances minus homers, walks and strikeouts). Since I used league batting rather than pitching data for this, there may be a slight discrepancy for the period since the start of interleague play in 1997.
NL/AL etc.: Under the league name I have the league’s DER for that season.
High/Low: The team with the league’s highest and lowest DERs. I used Baseball-Reference.com’s team abbreviations.
DER: That team’s DER
High%/Low%: Team DER divided by the league average. This is the key number I use to identify the best and worst defensive teams, so we can see who were the best and worst defensive teams relative to the league average. As usual, I’m not using any math here more complicated than simple arithmetic and basic algebra.
Also, where I compute “rough” estimates of BABIP for pre-1950 pitchers I used the basic formula of (H-HR)/((IP*3)+H-HR-K)
The 1870s
Talent levels in the 1870s were especially uneven, as the first organized league – the National Association – began play in 1871 just two years after the debut of the first-ever professional team. Schedules were short (20 games in 1871, in the 60s by decade’s end), fielders didn’t wear gloves, playing surfaces were ungroomed and in some cases effectively without fences, and with nine balls for a walk and longballs unheard of, nearly every plate appearance resulted in a ball in play – the 1872 season’s 96.5% rate is the highest in the game’s history, and 1879 was the last season above 90%.
As you can see, defenses improved dramatically over this period, in part no doubt as professional pitchers and fielders learned their craft and more of the nation’s best ballplayers gathered into the National Association and later the NL. But errors were a big chunk of the poor defense of the era – in each of the NL’s first five seasons, there were more unearned runs than earned runs scored, and it wasn’t until 1906 that the average number of unearned runs would drop below 1 per game.
The most successful defensive team of the era was the 1876 St. Louis “Brown Stockings” team (not precisely the same organization as the Cardinals), the only Major League team ever to be 10% better than its league in DER. Starting pitcher George “Grin” Bradley struck out 1.6 men per 9 innings but led the league with a 1.23 ERA (the team also allowed the league’s fewest runs, although their 2.36 unearned runs per 9 innings was only third-best in the league) while throwing all but four of the team’s innings. A rough estimate of the BABIP against Bradley is .258 in 1875, .224 in 1876, but .285 after he changed teams the next year, when his ERA nearly tripled, and .267 for his career. Which at least seems consistent with the notion that Bradley’s defense was doing most of the work.
Note that the Philadelphia Athletics of 1873-74, featuring Cap Anson and Ezra Sutton in their infield, made the only repeat appearance on the decade’s leaderboard (Anson, in his early 20s, played multiple positions including short and third, while Sutton was beginning a long career as a third baseman and shortstop).
The worst defensive team of all time? I hate to give you such an underwhelming answer, but by a wide margin it’s the 1873 Baltimore Marylands, who folded after just 6 winless games and almost none of whose players appeared in the big leagues again. The hapless Marylands allowed 144 runs in 6 games (24 per game), only 48 of which were earned; in addition to hideous defense their pitchers didn’t strike out a single batter. (The offense was no better, as a team batting average of .156 with only one extra base hit and no walks attest). When you think of the level of competition in those early years, think of the Marylands.
National Association-National League

	BIP%	NA	High	DER	High %	Low	DER	Low %
1871	94.5%	586	NYU	608	103.75%	TRO	548	93.52%
1872	96.5%	589	BOS	647	109.85%	OLY	510	86.59%
1873	96.2%	578	ATH	613	106.06%	MAR	458	79.24%
1874	96.7%	589	ATH	629	106.79%	BAL	552	93.72%
1875	96.4%	619	HAR	663	107.11%	WAS	538	86.91%
	BIP%	NL	High	DER	High %	Low	DER	Low %
1876	95.3%	626	STL	698	111.50%	CIN	569	90.89%
1877	92.2%	623	HAR	642	103.05%	CIN	561	90.05%
1878	89.5%	628	CIN	638	101.59%	MLG	615	97.93%
1879	90.2%	632	BUF	659	104.27%	TRO	599	94.78%

The 1880s
The game gradually professionalized in the 1880s, but not without a great many bumps along the way. The Union Association of 1884 was only barely a major league (four teams, including Wilmington, folded after playing less than a quarter of the schedule), but diluted the talent level of the two major leagues. The 4-ball/three-strike count wasn’t standardized until 1889, after a gradual decline in the number of balls for a walk and a one-year experiment in 1887 with four strikes for a strikeout; DERs rose sharply after the three-strike rule was restored. The schedule topped 100 games for the first time in 1884, and had reached 135 by 1888. The color line was established in the wake of the failure of Reconstruction (which effectively ended in 1877), after only a few black players had taken the field. The first gloves were becoming commonly used by decade’s end.
Anson’s 1882 White Stockings (now Cubs) and the 1882 Red Stockings (now Reds) became the first pennant-winning teams to lead the league in DER since the founding of the National League (in the NA, only the 1872 Boston team had done so); four teams would do so in each of the two leagues in ten years, plus the Union Association champs. Bid McPhee, enshrined in the Hall of Fame in 2000 largely for his defense, anchored the Red Stockings teams that led the league three times in their first six seasons in the league, and their 1882 and 1883 DERs were the most dominant of the decade outside the UA, but the mid-decade St. Louis Browns (now Cardinals) juggernaut also emerged as a defensive powerhouse. The woebegotten 1883 Philadelphia Quakers were the decade’s worst defensive team. The NL’s most successful defensive squad? The 1884 Providence Grays, much to the benefit of Old Hoss Radbourn, who had his famous 59-12, 1.38 ERA season. Radbourn also struck out 441 batters in 678.1 innings, so he did his share as well, and by a rough calculation the opposing BABIP of .242 – while a career best – wasn’t hugely out of line with his career .271 mark. Lucky and good is a good combination.
National League

	BIP%	NL	High	DER	High %	Low	DER	Low %
1880	88.8%	649	PRO	681	104.93%	BUF	615	94.76%
1881	88.6%	641	CHC	664	103.59%	BUF	613	95.63%
1882	87.4%	641	CHC	667	104.06%	WOR	590	92.04%
1883	86.3%	617	CLV	651	105.51%	PHI	553	89.63%
1884	81.2%	633	PRO	678	107.11%	DTN	611	96.52%
1885	83.8%	651	NYG	697	107.07%	BUF	613	94.16%
1886	81.1%	644	PHI	674	104.66%	KCN	602	93.48%
1887	84.7%	647	DTN	663	102.47%	WHS	635	98.15%
1888	83.9%	671	NYG	694	103.43%	IND	659	98.21%
1889	82.0%	650	CLV	673	103.54%	WHS	622	95.69%

American Association

	BIP%	AA	High	DER	High %	Low	DER	Low %
1882	89.3%	639	CIN	692	108.29%	BAL	599	93.74%
1883	87.5%	631	CIN	688	109.03%	PIT	591	93.66%
1884	83.7%	640	LOU	670	104.69%	WAS	580	90.63%
1885	84.5%	649	STL	679	104.62%	PHA	623	95.99%
1886	81.0%	643	STL	667	103.73%	PHA	625	97.20%
1887	84.5%	630	CIN	658	104.44%	NYP	595	94.44%
1888	82.8%	662	STL	702	106.04%	LOU	626	94.56%
1889	81.0%	640	BRO	665	103.91%	LOU	604	94.38%

Union Association

	BIP%	UA	High	DER	High %	Low	DER	Low %
1884	80.7%	591	SLM	644	108.97%	WIL	539	91.20%

The 1890s
The NL achieved dominance after the Players League war. The modern era of pitching arrived in 1893 when the mound was moved back from 50 feet to its current 60 feet 6 inches; the percentage of balls in play spiked as strikeouts became almost non-existent, while DERs plunged in 1894 and 1895, suggesting more hard-hit balls off pitchers struggling to adjust to the new distance. The 1890 Pirates were the decade’s worst defensive team, the 1895 Baltimore Orioles (with extra balls hidden in the long grass of the outfield among their notorious tricks) the best, although the late-decade Beaneaters (now Braves, featuring Hall of Famers Hugh Duffy and Billy Hamilton in the outfield, Jimmy Collins at third, and Kid Nichols as the staff ace) were consistently dominant and would remain so through 1901. (Collins left in 1901, Duffy the previous year, but Nichols, Hamilton and infield anchors Herman Long, Bobby Lowe and Fred Tenney were there the whole time; Long and Nichols had also been on the 1891 team). Four teams had the NL’s best record while leading the league in DER, three of them Beaneaters teams.
National League

	BIP%	NL	High	DER	High %	Low	DER	Low %
1890	81.8%	663	CHC	696	104.98%	PIT	598	90.20%
1891	82.1%	665	BSN	677	101.80%	CLV	645	96.99%
1892	82.2%	672	CLV	697	103.72%	BLN	625	93.01%
1893	84.4%	654	PIT	673	102.91%	WHS	614	93.88%
1894	84.9%	626	NYG	651	103.99%	WHS	601	96.01%
1895	85.5%	637	BLN	677	106.28%	LOU	606	95.13%
1896	85.9%	649	CIN	673	103.70%	WHS	625	96.30%
1897	86.0%	648	BSN	679	104.78%	STL	618	95.37%
1898	86.2%	669	BSN	708	105.83%	WHS	633	94.62%
1899	86.9%	660	BSN	699	105.91%	CLV	610	92.42%

American Association

	BIP%	AA	High	DER	High %	Low	DER	Low %
1890	80.2%	652	COL	692	106.13%	PHA	609	93.40%
1891	80.4%	653	COL	677	103.68%	WAS	605	92.65%

Players League

	BIP%	PL	High	DER	High %	Low	DER	Low %
1890	82.6%	636	NYI	655	102.99%	BUF	612	96.23%

The 1900s
The foul-strike rule, adopted in the NL in 1901 and the AL in 1903, brought back the strikeout and contributed, along with better gloves and more “small ball,” to rising DERs, as the NL in 1907 became the first league ever to turn 70% of balls in play into outs, rising to 71.4% in 1908, a level that would not be matched again until 1942. Schedules also started to be standardized in 1904, settling around 154 games after a decade mostly in the high 120s.
Surprisingly, defense was not the essential element for many of the pennant winners of the Dead Ball Era’s first decade – only one AL pennant winner (the 1903 Red Sox, featuring Jimmy Collins yet again) led the league, and only two NL pennant winners. That being said, the Cubs of the Tinker-Evers-Chance era have as good an argument as anyone to be the dominant defensive team of all time. They led the NL in DER eight times in nine years, as well as finishing a close second (at 726, 101.68% of the league) the ninth of those, and second again in 1912. In 1906, on the way to a 116-36 record, they became the first of five post-1900 teams to beat the league average by 5% or more, and their 736 DER bested the second-place Phillies by 29 points and would not be topped (in raw terms) for 62 years, by men using vastly superior equipment. It’s possible there was a park factor at work, although Baseball-Reference.com lists West Side Park (where the Cubs played until Wrigley opened in 1916) as if anything a hitters park until late in the decade; in 1906, the Cubs combined to score and allow 7.24 runs per game at home, 7.03 on the road, with the defense in particular allowing 2.22 runs per game on the road compared to 2.78 at West Side Park. Was it the pitchers? By my rough estimate, the BABIPs against four or the five pitchers on that staff to throw 1000 or more innings as Cubs between 1903 and 1912 -Three Finger Brown, Carl Lundgren, Orval Overall, and Jack Pfiester – varied between .237 and .241 compared to a team average of .241 for all pitchers to throw at least 200 innings on the team over those years, with only one such pitcher above .254. Only Ed Reulbach, at .230, seems to have stood out a bit. That suggests that the team’s defense was the predominant factor. The same BABIP figure for the rival Giants, a good but more normal defensive team, was .259 – the 19-point advantage on balls in play for Brown over Christy Mathewson is almost certainly the main explanation for why Brown’s ERA was better (1.75 to 1.90) over those years, although of course Brown was nonetheless a great pitcher.
Best AL defensive team? The 1901 Red Sox, another Jimmy Collins squad. Worst team of the decade? The unraveling 1902 Baltimore Orioles, who were deserted by John McGraw in mid-season and relocated to New York (now the Yankees) the following spring (like the prior year’s Milwaukee franchise – there’s a long history of teams getting folded or moved after cellar-dwelling DERs, as terrible defense is often a byproduct of organizational failure).
Also, note the atrocious showings by the late-decade Washington Senators, the team on which Walter Johnson broke in, yet another way in which Johnson’s early career was plagued by bad teams. Johnson would bear some closer study – a quick look suggests that his BABIPs may have been better than his teams’ for much of his career, as if he needed more advantages on top of leading the AL in K/BB ratio nine times, K/9 seven times, fewest BB/9 twice and fewest HR/9 three times (a favorite stat: Johnson in 1918-19 threw 616.1 innings and allowed just two home runs, both of them by Babe Ruth). His BABIP seems to have hit a career low of .219 in 1913 at the same time as his career high 6.39 K/BB ratio, another example of perhaps being both lucky and good, or perhaps there being a correlation between the two.
National League

	BIP%	NL	High	DER	High %	Low	DER	Low %
1900	86.3%	661	BSN	691	104.54%	NYG	637	96.37%
1901	83.3%	664	BSN	685	103.16%	CIN	640	96.39%
1902	84.3%	674	BRO	696	103.26%	STL	648	96.14%
1903	83.5%	664	CHC	681	102.56%	STL	647	97.44%
1904	83.7%	688	CHC	709	103.05%	PHI	658	95.64%
1905	82.9%	683	CHC	716	104.83%	BRO	649	95.02%
1906	82.0%	698	CHC	736	105.44%	BSN	670	95.99%
1907	82.8%	702	CHC	730	103.99%	BSN	685	97.58%
1908	83.7%	714	PIT	730	102.24%	STL	698	97.76%
1909	82.2%	698	CHC	721	103.30%	BSN	680	97.42%

American League

	BIP%	AL	High	DER	High %	Low	DER	Low %
1901	86.4%	658	BOS	684	103.95%	MLA	647	98.33%
1902	86.2%	671	BOS	686	102.24%	BLA	636	94.78%
1903	83.8%	680	BOS	695	102.21%	WSH	668	98.24%
1904	82.9%	693	CHW	716	103.32%	WSH	668	96.39%
1905	81.8%	697	CHW	721	103.44%	NYY	688	98.71%
1906	83.3%	692	CLE	719	103.90%	WSH	672	97.11%
1907	83.7%	693	BOS	710	102.45%	WSH	666	96.10%
1908	82.7%	700	CHW	719	102.71%	NYY	680	97.14%
1909	82.3%	695	PHA	717	103.17%	SLB	676	97.27%

The 1910s
Defense had the upper hand in the teens, with DERs regularly topping 70% leaguewide in the second half of the decade, especially in the NL. If top defensive teams winning the pennant were a rarity in the prior decade, they became routine in the teens – five times in the NL, five in the AL. The Red Sox were the decade’s dominant team in the AL both defensively and overall, and continued to lead the league even after the departure in 1916 of Tris Speaker. (Oddly, the Red Sox went from the best DER in the AL in 1912 to the worst in 1913 and back to the best in 1914; more on that below.) Meanwhile, the NL’s revolving door of pennant winners (and World Series doormats) from 1915-19 were generally whoever handled the balls in play best. Yet most of those NL teams didn’t beat the league average by all that much, and the best single-season showing was the 1919 Yankees. The worst, unsurprisingly, was the post-fire-sale 1915 A’s (with a fossilized 40-year-old Nap Lajoie at second and their best remaining player, catcher Wally Schang, playing out of position at third), although the doormat 1911 Braves weren’t far behind.
The Cubs’ defense stopped being dominant with the 1913 departure of Joe Tinker, who went on to anchor the Federal League’s best defense, while Johnny Evers was part of lifting those Braves out of their 1911-12 defensive funk to a slightly above average defensive team in 1914 (they’d been below average in 1913 – that said, I’d expected the 1914 Miracle Braves to be one of the teams that had a huge year defensively, and even with Evers and Rabbit Maranville, they didn’t).
National League

	BIP%	NL	High	DER	High %	Low	DER	Low %
1910	81.4%	688	CHC	708	102.91%	STL	673	97.82%
1911	80.1%	684	CHC	698	102.05%	BSN	649	94.88%
1912	81.2%	679	PIT	703	103.53%	BSN	659	97.05%
1913	81.8%	691	NYG	702	101.59%	CIN	684	98.99%
1914	81.5%	698	PIT	712	102.01%	PHI	666	95.42%
1915	82.1%	704	PHI	715	101.56%	NYG	687	97.59%
1916	82.3%	704	BRO	719	102.13%	STL	684	97.16%
1917	83.2%	704	NYG	723	102.70%	CHC	691	98.15%
1918	85.2%	707	NYG	723	102.26%	BSN	695	98.30%
1919	85.2%	705	CIN	729	103.40%	PHI	672	95.32%

American League

	BIP%	AL	High	DER	High %	Low	DER	Low %
1910	81.7%	692	PHA	713	103.03%	SLB	663	95.81%
1911	80.6%	662	CHW	675	101.96%	WSH	655	98.94%
1912	80.5%	666	BOS	683	102.55%	NYY	640	96.10%
1913	81.1%	685	PHA	701	102.34%	BOS	670	97.81%
1914	80.2%	692	BOS	709	102.46%	CLE	662	95.66%
1915	80.1%	693	BOS	712	102.74%	PHA	654	94.37%
1916	80.9%	698	BOS	713	102.15%	PHA	668	95.70%
1917	82.4%	704	BOS	724	102.84%	PHA	687	97.59%
1918	83.5%	705	BOS	729	103.40%	DET	694	98.44%
1919	83.1%	689	NYY	715	103.77%	PHA	661	95.94%

Federal League

	BIP%	FL	High	DER	High %	Low	DER	Low %
1914	80.7%	679	CHI	711	104.71%	SLM	667	98.23%
1915	81.9%	694	CHI	708	102.02%	BAL	660	95.10%

The 1920s
Lower strikeout rates with the lively ball’s arrival were probably the largest factor in the sudden increase in scoring in the Twenties, as even the gradual arrival of home run hitters and a leaguewide rise in walks couldn’t stop the upward march of the percentage of balls in play. But DERs dropped a good 15 points as well.
Defense was slightly more the hallmark of AL than NL pennant winners in the Twenties – six in the AL, four in the NL. Naturally the 1927 Yankees were the best in the league at this, too, their fifth league lead in nine years. And Walter Johnson finally got some real defensive support when the Senators won their two pennants in 1924-25, dropping Johnson’s BABIP from .280 to .248 in 1924.
As discussed in the next decade, you have to figure a significant park effect was at work in the fact that the Phillies were dead last in the NL in DER 14 times in their last 17 full seasons in the Baker Bowl, including the NL’s worst showing of the decade in 1926. Then again, nearly all of those Phillies teams were terrible teams, with a collective .383 winning percentage and only one winning record, in 1932 when their DER was 98.5% of the league average. And the Phillies had led the league in DER behind Grover Alexander in 1915.
National League

	BIP%	NL	High	DER	High %	Low	DER	Low %
1920	85.3%	693	CIN	708	102.16%	STL	678	97.84%
1921	85.6%	680	PIT	696	102.35%	PHI	658	96.76%
1922	84.7%	677	NYG	700	103.40%	STL	663	97.93%
1923	84.5%	681	CHC	700	102.79%	PHI	651	95.59%
1924	84.8%	687	PIT	704	102.47%	PHI	665	96.80%
1925	84.3%	676	CIN	689	101.92%	PHI	659	97.49%
1926	84.6%	689	STL	707	102.61%	PHI	656	95.21%
1927	84.4%	687	PIT	705	102.62%	PHI	663	96.51%
1928	83.6%	693	STL	707	102.02%	PHI	666	96.10%
1929	83.1%	680	PIT	692	101.76%	PHI	662	97.35%

American League

	BIP%	AL	High	DER	High %	Low	DER	Low %
1920	83.7%	677	NYY	689	101.77%	PHA	656	96.90%
1921	83.5%	674	BOS	683	101.34%	PHA	666	98.81%
1922	83.6%	687	NYY	707	102.91%	CLE	669	97.38%
1923	83.1%	686	NYY	709	103.35%	WSH	673	98.10%
1924	83.9%	682	WSH	709	103.96%	CHW	666	97.65%
1925	83.3%	679	WSH	689	101.47%	BOS	662	97.50%
1926	83.2%	689	CLE	702	101.89%	DET	677	98.26%
1927	83.6%	684	NYY	701	102.49%	SLB	666	97.37%
1928	83.2%	687	PHA	700	101.89%	CLE	665	96.80%
1929	83.0%	687	PHA	703	102.33%	DET	664	96.65%

The 1930s
1935 saw the arrival of night baseball, which would eventually be a factor in bringing back strikeout rates, as would the growth of relief pitching, still taking its first baby steps in the Thirties; between those factors and more home runs, the AL in 1937 became the first major league in which less than 80% of plate appearances resulted in a ball in play, after being above 83% in the AL and 84% in the NL for much of the Twenties. Six AL pennant winners had the league’s best DER, compared to just two in the NL.
The 30s were the best and worst of times. The Phillies hit their nadir in 1930, at 631 the worst raw DER since 1900 (the 1911 Braves being the only other team since 1906 to finish below 650), the worst relative to the league since the ill-fated 1899 Cleveland Spiders and the only team lower than 95% of the league average since the 1915 A’s. Not for nothing did they post a modern-record 6.71 team ERA, allow 7.69 runs per game, and lose nearly two-thirds of their games even with Lefty O’Doul batting .383/.453/.604 and scoring 122 runs and Chuck Klein (probably the most park-created of all Hall of Famers) batting .386/.436/.687 with 158 runs scored and 170 RBI. Then again, they also had the league’s worst K/BB ratio and allowed the league’s most homers, so it wasn’t all the defense’s fault. And the Phillies left the Baker Bowl for good at the end of June 1938, and still finished last in DER in 1938 and 1941 plus three more times in the mid-1940s.
In the AL, the late-30s St. Louis Browns, presumably despite Harlond Clift at third, were the league’s worst, hitting bottom in 1939. Also in St. Louis, if you’re curious, the 1934 “Gashouse Gang” Cardinals team was league-average.
On the positive end, we have the 1900s Cubs’ top competition for the title of the best defensive team of all time, the 1939 Yankees, the team that Rob Neyer and Eddie Epstein (measuring by runs scored and allowed relative to the league) marked as the greatest team of all time in “Baseball Dynasties,” noting that they led the league in runs scored and fewest runs allowed four years in a row. So it’s not surprising to encounter them here. The Yankees’ DER was the furthest above their league of any team since 1885, and their 730 DER led the league by 35 points. This was part of a string of six straight seasons and 12 in 13 years when they had the league’s most successful defense, starting in Babe Ruth’s last year two years before the arrival of Joe DiMaggio and running clear through World War II. While a number of players appeared on many of those teams (DiMaggio, Tommy Henrich, Frank Crosetti, Red Rolfe, Joe Gordon), the only constants were manager Joe McCarthy and catcher Bill Dickey. (Both had also been on the 1933 team that was last in the AL in DER before cutting back the Babe’s playing time and putting Earle Combs and Joe Sewell, both 34, out to pasture). You have to give McCarthy some of the credit for the Yankees’ consistent defensive excellence, if only in how he chose to distribute playing time.
That said, a significant park effect can’t be discounted here. Yankee Stadium was always a pitcher’s park, and seems to have been a particularly extreme one in 1939: unlike for the Cubs, we have home/road detailed splits for the 1939 Yankees, which show that Yankee hitters had a BABIP of .273 at home, .315 on the road, while Yankee opponents had a BABIP of .248 at home, .267 on the road – combined, .260 at home, .292 on the road. I haven’t had time to run the splits for the Yankees’ whole run in that period – this essay took up quite enough of my time, and it would be a worthwhile project for someone else to carry on further – but even on the basis of the huge split for 1939, as remarkable as the Yankees’ defensive performance was in the McCarthy era, it has to be taken with the same grain of salt as the Baker Bowl era Phillies. (The 1930 Phillies’ Home/Road BABIP splits were .352/.300 for their offense, .365/.341 for their pitching staff, and a combined line of .358/.321 – a 36-point spread)
Speaking of managers, Walter Johnson may not have had great defenses as a pitcher, but as a manager he did better, skippering the Senators to two league-best DERs in four years from 1929-32. And the 1938 Braves became the first Casey Stengel-managed team to lead the league in DER, albeit a squad he inherited from Bill McKechnie with the decade’s best DER in the NL in 1937.
National League

	BIP%	NL	High	DER	High %	Low	DER	Low %
1930	82.8%	669	BRO	693	103.59%	PHI	631	94.32%
1931	83.4%	687	NYG	706	102.77%	PHI	666	96.94%
1932	84.0%	691	PIT	702	101.59%	STL	673	97.40%
1933	85.1%	702	NYG	719	102.42%	PHI	682	97.15%
1934	82.9%	685	NYG	704	102.77%	CIN	666	97.23%
1935	83.2%	686	NYG	707	103.06%	PHI	667	97.23%
1936	82.7%	684	CHC	698	102.05%	PHI	666	97.37%
1937	81.3%	689	BSN	714	103.63%	PHI	670	97.24%
1938	82.1%	697	BSN	711	102.01%	PHI	675	96.84%
1939	81.7%	695	CIN	708	101.87%	PIT	682	98.13%

American League

	BIP%	AL	High	DER	High %	Low	DER	Low %
1930	82.0%	678	WSH	702	103.54%	CLE	661	97.49%
1931	82.0%	683	PHA	708	103.66%	SLB	667	97.66%
1932	81.2%	688	WSH	703	102.18%	CHW	674	97.97%
1933	81.5%	694	WSH	709	102.16%	NYY	682	98.27%
1934	80.2%	684	NYY	703	102.78%	CHW	677	98.98%
1935	81.2%	687	NYY	713	103.78%	WSH	668	97.23%
1936	80.5%	676	NYY	690	102.07%	SLB	657	97.19%
1937	79.5%	683	NYY	697	102.05%	SLB	658	96.34%
1938	79.2%	685	NYY	694	101.31%	SLB	671	97.96%
1939	79.9%	687	NYY	730	106.26%	SLB	660	96.07%

The 1940s
In the 1940s, change was in the winds. The war decimated MLB’s talent level and introduced inferior baseballs (due to wartime shortages) that traveled poorly when hit. DERs rose back above 70% even before the war in the NL, and in 1942 in the AL. After the war, integration followed and the game was off to the races, while night baseball really came into its own.
In the NL, defense was king – seven pennant winners led the league in DER in nine years between 1939-47, plus the 104-win second-place 1942 Dodgers; four pennant winners led the AL, but three of those were the 1941-43 Yankees. The strongest defensive teams of the decade were McKechnie’s 1940 Reds and Lou Boudreau’s 1948 Indians (a team famous for its outstanding infield of Boudreau, Ken Keltner, Joe Gordon and Eddie Robinson), the weakest the 1940 Pirates and 1942 Senators (the difference between the Senators of the mid-40s and the Indians of the 50s explains a lot about Early Wynn’s career). The chicken-egg question remains regarding good defenses and successful managers, as Leo Durocher’s arrival in Brooklyn in 1939 and Billy Southworth’s in St. Louis in 1940 were followed within a few years by the construction of superior defensive teams.
The 1947 Reds were the third and last team to go from first to last in the league in DER in a single season, after the 1913 Red Sox and 1880 Buffalo Bisons:

Team	Years	DER1	DER2	Change	Change %
BUF	1879-80	659	615	-44	93.3%
CIN	1946-47	716	693	-23	96.8%
BOS	1912-13	683	670	-13	98.1%

The Bisons and their ace pitcher, Hall of Famer Pud Galvin, hail from baseball’s ancient past, and the Red Sox were a bit of a fluke, given the small size of their decline and their rapid rebound the following year. What of the 1947 Reds? 1946 was the last season of McKechnie’s career, and McKechnie was notoriously defense-obsessed. The team gave a lot more playing time to 30-year-old shortstop Eddie Miller, outfielder Frank Baumholtz and noodle-armed 35-year-old left fielder Augie Galan. Sidearmer Ewell Blackwell had his big breakthrough season in 1947, improving his K/BB from 1.27 to a league-leading 2.03, but saw his ERA slip slightly from 2.45 to 2.47, while veterans Johnny Vander Meer and Bucky Walters got completely wiped out by the defensive collapse.
National League

	BIP%	NL	High	DER	High %	Low	DER	Low %
1940	81.5%	701	CIN	730	104.14%	PIT	676	96.43%
1941	80.9%	704	BRO	732	103.98%	PHI	683	97.02%
1942	81.2%	716	BRO	734	102.51%	CHC	699	97.63%
1943	82.1%	707	STL	719	101.70%	NYG	691	97.74%
1944	82.3%	707	STL	733	103.68%	CHC	689	97.45%
1945	82.1%	701	CHC	718	102.43%	PHI	674	96.15%
1946	80.2%	709	CIN	716	100.99%	PHI	697	98.31%
1947	79.3%	703	BRO	720	102.42%	CIN	693	98.58%
1948	79.0%	704	BSN	714	101.42%	PHI	694	98.58%
1949	79.3%	707	NYG	722	102.12%	CHC	684	96.75%

American League

	BIP%	AL	High	DER	High %	Low	DER	Low %
1940	79.1%	691	CHW	715	103.47%	WSH	675	97.68%
1941	79.7%	698	NYY	714	102.29%	WSH	680	97.42%
1942	80.9%	706	NYY	721	102.12%	WSH	676	95.75%
1943	80.5%	714	NYY	725	101.54%	SLB	703	98.46%
1944	81.9%	702	NYY	712	101.42%	WSH	692	98.58%
1945	81.3%	707	NYY	716	101.27%	CHW	692	97.88%
1946	78.4%	703	NYY	715	101.71%	SLB	690	98.15%
1947	78.9%	712	CLE	734	103.09%	WSH	697	97.89%
1948	78.8%	704	CLE	731	103.84%	SLB	685	97.30%
1949	77.7%	707	CLE	724	102.40%	SLB	680	96.18%

Part II here.

Part I here.
The 1950s
Baseball started moving west with the Braves’ move to Milwaukee in 1953, and the resulting shakeup ended the stranglehold of old, mostly smaller ballparks in the East. High walk rates, more power hitters and a few more strikeouts meant that balls in play rates were dropping, while defenses got stingier – the 71.6% of balls in play turned into outs in the NL in 1956 remains the league record.
I’ve written before about the advantage Casey Stengel’s Yankees got from their defense and how it played into the superior performance of pitchers in pinstripes. But it was the Indians who were the true defensive juggernaut of that era, leading the AL seven times in the decade between 1947-56. The AL was truly defensively stratified in those years, with the upper tier of the Yankees, Indians and White Sox at the top and weak sisters like the Browns, Senators, A’s and Tigers at the bottom. Park effects were part of that picture for the Yankees – for example, in 1955 the Yankees and their opponents had a BABIP of .265 at home, .278 on the road, compared to .272 at home, .269 on the road for the 1954 Indians.
The 111-win Indians were the best defensive team of the decade (the 1909 Pirates, who finished one point behind the Cubs, are the only team to win 110 games in a season without leading the league in DER), Durocher’s 1950 Giants the best NL team, the 1955 Pirates and 1950 Browns the worst; the Pirates were perennially hapless. Four pennant-winning teams in each league led the league in DER, although as I’ve noted the Yankees often finished second or third in DER while winning the pennant, and the 1953 Dodgers and 1957 Braves just narrrowly missed the league lead.
I’d expected the Ashburn-era Phillies to lead the league more than once; the strangest league leaders were the 1952 Cubs, an also-ran team that featured one of the more plodding sluggers (Hank Sauer) ever to win the MVP.
National League

	BIP%	NL	High	DER	High %	Low	DER	Low %
1950	77.7%	707	NYG	729	103.11%	CHC	693	98.02%
1951	78.9%	711	NYG	721	101.41%	PIT	697	98.03%
1952	78.1%	713	CHC	723	101.40%	PIT	703	98.60%
1953	77.5%	702	MIL	715	101.85%	PIT	687	97.86%
1954	77.8%	707	NYG	722	102.12%	PIT	687	97.17%
1955	76.8%	714	PHI	728	101.96%	PIT	688	96.36%
1956	76.8%	716	BRO	730	101.96%	PIT	702	98.04%
1957	76.6%	706	BRO	717	101.56%	CHC	698	98.87%
1958	75.8%	703	MLN	721	102.56%	LAD	693	98.58%
1959	75.4%	701	CHC	714	101.85%	STL	685	97.72%

American League

	BIP%	AL	High	DER	High %	Low	DER	Low %
1950	77.6%	700	CLE	721	103.00%	SLB	676	96.57%
1951	78.6%	706	CLE	720	101.98%	SLB	686	97.17%
1952	77.9%	713	CHW	723	101.40%	DET	700	98.18%
1953	78.5%	706	CHW	720	101.98%	DET	682	96.60%
1954	77.9%	711	CLE	735	103.38%	PHA	689	96.91%
1955	76.7%	710	NYY	733	103.24%	WSH	689	97.04%
1956	75.3%	705	CLE	722	102.41%	WSH	683	96.88%
1957	76.6%	713	NYY	727	101.96%	WSH	694	97.34%
1958	76.2%	712	NYY	726	101.97%	WSH	697	97.89%
1959	76.0%	712	CLE	730	102.53%	KCA	691	97.05%

The 1960s
Rising strikeout rates, with the onset of expansion, new pitchers’ parks in LA and Houston, and the expansion of the strike zone in 1963, are a major part of the story of pitching dominance in the Sixties; the AL in 1961, the year of Maris and Mantle, became the first league to see balls in play drop below 75% of plate appearances, and by 1964 it was down to 72.9%, the lowest it would be until 1987. Unsurprisingly, that started to loosen the relationship between defense and success – only three NL pennant winners led the league in DER, four in the AL, and the 1967 Twins came within a game of becoming the first team to finish first while being last in the league in DER.
Meanwhile, the story on balls in play showed a real split between the leagues: DERs actually declined in the NL, while reaching historic highs in the AL. The 724 DER in the AL in 1968 is the highest in Major League history, and the 743 figure by the 1969 Orioles is the highest ever recorded by a team. That Brooks Robinson-Mark Belanger-Davey Johnson infield and Paul Blair-led outfield really was impenetrable, and even adjusted for the league was the best of the decade, powering the O’s to 109 wins. (Home/road split: .275 at home, .278 on the road).
The Dodgers of the Sixties did well on balls in play, even as they dominated the pitcher-controlled aspects of defense (if I recall correctly, the 1966 Dodgers still hold the team K/BB ratio record).
The 1962 Mets, surprisingly, did not have the league’s worst DER (unlike the 1969 Seattle Pilots), finishing a point above the Astros; the 1969 Mets did lead the league (in fact, they led three years in a row from 1968-70), but other surprise teams of the decade did not – the 1967 Red Sox were just below the league average at 715, and the 1960 Pirates were also below average. Probably no team in this sample surprised me more with their poor defensive stats than the Pirates of the 1960s, finishing last in DER in 1961 and 1964 despite a lineup stocked with legendary defensive players like Bill Mazeroski, Roberto Clemente and Bill Virdon as well as other respected glove men like Dick Schofield Sr. The other surprise, more on which later, was the persistent poor performance of the Astros.
The Yankee dynasty’s collapse was reflected defensively, as the Yankees were second in DER in 1964 (at 726), but ninth in 1965 at 707.
National League

	BIP%	NL	High	DER	High %	Low	DER	Low %
1960	75.0%	703	LAD	714	101.56%	PHI	694	98.72%
1961	75.0%	699	MLN	721	103.15%	PIT	683	97.71%
1962	74.7%	695	SFG	710	102.16%	HOU	680	97.84%
1963	74.8%	706	MLN	721	102.12%	NYM	694	98.30%
1964	75.7%	698	LAD	709	101.58%	PIT	682	97.71%
1965	74.5%	704	LAD	727	103.27%	PHI	687	97.59%
1966	75.4%	699	STL	712	101.86%	HOU	687	98.28%
1967	75.1%	703	SFG	719	102.28%	HOU	683	97.16%
1968	75.8%	707	NYM	719	101.70%	HOU	690	97.60%
1969	73.6%	701	NYM	729	103.99%	HOU	683	97.43%

American League

	BIP%	AL	High	DER	High %	Low	DER	Low %
1960	75.8%	712	NYY	732	102.81%	BOS	688	96.63%
1961	74.7%	708	BAL	731	103.25%	KCA	689	97.32%
1962	74.7%	710	NYY	719	101.27%	LAA	702	98.87%
1963	74.4%	713	NYY	725	101.68%	WSA	701	98.32%
1964	72.9%	711	CHW	733	103.09%	BOS	683	96.06%
1965	73.3%	715	CHW	728	101.82%	BOS	692	96.78%
1966	73.9%	717	CHW	728	101.53%	BOS	704	98.19%
1967	73.4%	718	CHW	735	102.37%	MIN	704	98.05%
1968	74.0%	724	BAL	740	102.21%	WSA	702	96.96%
1969	73.7%	714	BAL	743	104.06%	SEP	691	96.78%

The 1970s
In the 1970s, even after the arrival of the DH, AL teams with top defenses tended to finish first in their divisions – 8 times in 11 years from 1969-79. In the NL, it was a different story, as teams like the Big Red Machine and the late-70s Pirates seemed often to lead the league in years other than the years those same teams finished first. The Dodgers led the league in DER four times between 1972 and 1978, and won the division the three years they didn’t.
You’ve met two of the five teams since 1900 to better the league average in DER by 5% or more, the 1906 Cubs and 1939 Yankees, both great teams that left the rest of their league in the dust. But the third team was one left in the dust by another juggernaut: the 1975 Dodgers, who led the league in DER by 20 points over the 108-win Reds, while finishing 20 games behind them (it didn’t help that the Dodgers underperformed their Pythagorean record by 7 games). Oddly, the very best Dodger defense came in a season when Bill Russell missed a good deal of time, but the then-youthful infield of Garvey, Lopes and Cey was otherwise tremendously durable, while 33-year-old Jimmie Wynn anchored the outfield defense (Wynn had also played on those late-60s Astros teams that perennially finished last in DER; go figure). Park effect? The Dodgers and their opponents combined for a .268 BABIP at home, .276 on the road, so the park seems to have had something to do with it. What about a pitching staff effect? Knuckleballer Charlie Hough had the team’s lowest BABIP (.219), but Hough threw only 61 innings. 321 innings were thrown by curveballer Andy Messersmith, and there may be something to that – pitcher BABIP are available since 1950, and Messersmith has the lowest career BABIP of any pitcher with 2000 or more career innings at .243 (rounding out the top 10, he’s followed by Catfish Hunter at .246, Hoyt Wilhelm at .250, Jim Palmer at .251, Hough at .253, Mudcat Grant at .258, Koufax at .259, Early Wynn at .260, and Tom Seaver and Warren Spahn at .262). The fact that that persisted across three teams (Angels, Dodgers and Braves) before he broke down in 1977 and that only Hunter’s even close to him suggests that Messersmith may have had some ability in that area. On the other hand, you have knuckle-curve specialist Burt Hooton, making the case for it being the team: Hooton’s BABIPs with the Cubs from 1972-94 were .278, .303 and .322, and .400 in the early going in 1975; after arriving with the Dodgers it dropped to .236, and was .253 over the next three seasons. Whether that’s the defense or the park, it’s evident that Hooton’s sudden improvement was due to the environment he pitched in.
The best AL defense of the decade was the Orioles again in 1973 (featuring much of the same cast, but this time with Bobby Grich at second); Earl Weaver’s defenses remained outstanding for years, as did Billy Martin’s when he arrived in New York (and brought in Paul Blair, among others). The worst were the 1974 Cubs and 1970 White Sox. Those Cubs featured Bill Madlock at third, 31 year old Don Kessinger at short, and an outfield of three guys who later became professional pinch hitters (Rick Monday, Jose Cardenal and Jerry Morales) and a DH at first (Andre Thornton). That said, BABIPs were higher at home – .312 at home, .296 on the road – so even aside from the home run ball, the park likely exaggerated the Cubs’s defensive failings in that era. Not for nothing did Rick Reuschel retire with a career BABIP of .294.
National League

	BIP%	NL	High	DER	High %	Low	DER	Low %
1970	73.3%	697	NYM	721	103.44%	STL	686	98.42%
1971	75.6%	706	CIN	727	102.97%	STL	689	97.59%
1972	74.7%	707	LAD	721	101.98%	HOU	695	98.30%
1973	75.1%	704	LAD	729	103.55%	CHC	687	97.59%
1974	75.9%	702	ATL	720	102.56%	CHC	672	95.73%
1975	76.3%	700	LAD	737	105.29%	CHC	673	96.14%
1976	77.0%	704	LAD	723	102.70%	SFG	691	98.15%
1977	75.2%	698	PIT	711	101.86%	ATL	677	96.99%
1978	76.2%	706	MON	718	101.70%	CIN	697	98.73%
1979	76.3%	700	HOU	719	102.71%	CHC	680	97.14%

American League

	BIP%	AL	High	DER	High %	Low	DER	Low %
1970	73.7%	710	OAK	728	102.54%	CHW	684	96.34%
1971	74.8%	714	OAK	730	102.24%	CHW	701	98.18%
1972	75.3%	718	BAL	740	103.06%	BOS	699	97.35%
1973	75.7%	701	BAL	731	104.28%	TEX	683	97.43%
1974	77.0%	702	BAL	716	101.99%	MIN	691	98.43%
1975	76.1%	703	BAL	731	103.98%	DET	683	97.16%
1976	77.7%	705	NYY	729	103.40%	CHW	693	98.30%
1977	76.3%	698	NYY	714	102.29%	CHW	682	97.71%
1978	77.7%	706	NYY	723	102.41%	TOR	690	97.73%
1979	77.4%	700	BAL	727	103.86%	OAK	678	96.86%

The 1980s
DERs in the AL finally dropped back in line with the NL by the late 70s, and the two leagues have mostly remained even since then. Balls in play percentages dropped in 1986, perhaps reflecting the rise in strikeouts occasioned by, among other things, the popularity of the split finger fastball and the increasing specialization of bullpens.
Best defensive team of the 80s: the Billyball A’s of 1980. In the NL: the far less remembered 1982 Padres. Worst: the 1981 Indians and 1984 Giants. The Whitaker-Trammell-Chet Lemon Tigers also stand out, although they are not as remembered as a defensive unit (but see the career of Walt Terrell). Their DER was also 713 when they had their big year in 1984, 705 in 1987.
The 1980s might be the decade that defense mattered least. Only two teams, the 1985 Blue Jays and 1989 A’s, finished first while leading the league in DER; the 1982 Giants came within two games of being the first team to finish first while being last in the league in DER, and a year later the “Wheeze Kids” Phillies turned the trick, remaining to this day the only team to be first in the standings and last in DER (the league hit .286 on BABIP against Cy Young winner John Denny, .329 against Steve Carlton). Those two teams had two things in common – an aging lineup (which for the Giants included Darrell Evans and Reggie Smith, the Phillies Pete Rose, Tony Perez, Gary Maddox, Mike Schmidt and Gary Matthews) and specifically, Joe Morgan at second base. I have to wonder about Morgan – it’s not a surprise that he would be found on poor defensive teams as his bat kept a decaying glove in the lineup in his late 30s (don’t forget, these were still good teams), but the Reds’ only league lead in DER in the 70s was in 1971, the year before Morgan’s arrival, and the Astros had routinely finished last during his years as their second baseman in the 60s. Could all be a coincidence, as Morgan’s defensive stats seem to suggest he was a fine glove man in his prime, but it bears closer examination.
The 1989 Yankees became the first Yankees team to finish last in the league in DER since 1933. The Mets finished second in the NL in DER in 1985, third in 1986. The Red Sox at 686 were below average in 1986, but at least not in the cellar as they were in 1985 and 1987.
National League

	BIP%	NL	High	DER	High %	Low	DER	Low %
1980	77.0%	700	LAD	715	102.14%	CHC	680	97.14%
1981	77.2%	704	HOU	721	102.41%	CHC	686	97.44%
1982	76.3%	701	SDP	725	103.42%	SFG	688	98.15%
1983	74.9%	702	HOU	718	102.28%	PHI	685	97.58%
1984	75.1%	698	SDP	721	103.30%	SFG	676	96.85%
1985	75.0%	706	STL	718	101.70%	ATL	691	97.88%
1986	73.3%	700	HOU	721	103.00%	CHC	678	96.86%
1987	73.1%	696	PIT	711	102.16%	CHC	677	97.27%
1988	75.3%	708	CIN	723	102.12%	ATL	692	97.74%
1989	74.3%	709	SFG	725	102.26%	PHI	699	98.59%

American League

	BIP%	AL	High	DER	High %	Low	DER	Low %
1980	77.7%	698	OAK	727	104.15%	TEX	676	96.85%
1981	77.6%	711	DET	740	104.08%	CLE	678	95.36%
1982	76.6%	704	DET	725	102.98%	CHW	688	97.73%
1983	77.0%	699	DET	726	103.86%	CAL	683	97.71%
1984	76.1%	699	BAL	715	102.29%	SEA	683	97.71%
1985	75.2%	703	TOR	724	102.99%	BOS	690	98.15%
1986	73.5%	699	DET	719	102.86%	SEA	670	95.85%
1987	72.7%	697	CHW	714	102.44%	BOS	674	96.70%
1988	75.1%	702	DET	718	102.28%	CLE	692	98.58%
1989	75.3%	698	OAK	715	102.44%	NYY	683	97.85%

The 1990s
DERs dropped sharply in 1993, inaugurating the era of…well, the Steroids Era, if you prefer. Or in the NL, perhaps the Mile High/Coors era. There were also ever fewer balls in play, with more and more homers, strikeouts and walks. Four NL teams finished first in DER and first in their division, three AL teams including the 1998 Yankees (the only Jeter-era Yankees team to finish either first or last in DER).
The worst defensive teams of the decade were the 1999 Rockies and 1997 A’s (the start of the “Moneyball” era – the A’s often fielded Jason Giambi and Matt Stairs in the outfield corners – although the winning A’s teams of a few years later would be above-average defensively, leading the AL in 2005). The Rockies’ home/road splits were so vast – .374 at home, .306 on the road in 1999 – that it’s almost impossible to evaluate their defense as such.
The 1990s also brought us the fourth of the five great defensive teams, the 1999 Reds, who led the league by a margin of 17 points over the Mets on the way to losing a one-game playoff for the wild card when their bats were stifled by Al Leiter. That Reds team is not recalled as widely as a great defense – it was the Mets that year who got the Sports Illustrated cover asking if they had the best infield ever – but with Barry Larkin, Mike Cameron and Pokey Reese, they had an outstanding defensive unit. Their home/road splits – .306 at home, .312 on the road – suggest that they did it without a huge amount of help from their home park.
National League

	BIP%	NL	High	DER	High %	Low	DER	Low %
1990	74.4%	701	MON	713	101.71%	ATL	676	96.43%
1991	74.0%	706	ATL	714	101.13%	NYM	689	97.59%
1992	74.8%	705	CHC	716	101.56%	LAD	685	97.16%
1993	74.2%	692	ATL	711	102.75%	COL	664	95.95%
1994	72.8%	688	SFG	707	102.76%	COL	664	96.51%
1995	71.9%	688	CIN	699	101.60%	PIT	669	97.24%
1996	71.5%	687	STL	706	102.77%	HOU	667	97.09%
1997	71.2%	688	LAD	706	102.62%	COL	667	96.95%
1998	71.3%	689	ARI	704	102.18%	FLA	669	97.10%
1999	70.7%	687	CIN	722	105.09%	COL	659	95.92%

American League

	BIP%	AL	High	DER	High %	Low	DER	Low %
1990	74.4%	699	OAK	732	104.72%	CAL	681	97.42%
1991	74.1%	699	CHW	728	104.15%	CLE	678	97.00%
1992	75.0%	702	MIL	725	103.28%	TEX	680	96.87%
1993	73.7%	693	BAL	704	101.59%	MIN	679	97.98%
1994	72.3%	687	BAL	706	102.77%	SEA	669	97.38%
1995	72.3%	690	BAL	716	103.77%	DET	672	97.39%
1996	71.7%	683	MIN	694	101.61%	BOS	665	97.36%
1997	71.6%	684	BAL	699	102.19%	OAK	660	96.49%
1998	72.0%	686	NYY	708	103.21%	TEX	668	97.38%
1999	71.8%	683	ANA	699	102.34%	TBD	661	96.78%

The 2000s
Is defense the new market inefficiency? Maybe in the National League, as eight first-place teams led the league in DER between 2000 and 2010 compared to three in the AL (plus the 2002 Angels, who didn’t finish first but did win 99 games and the World Series). Even with BIP percentages dropping, marginal advantages in defense can still help make a division winner.
Worst DERs of the decade: the 2007 Rays and Marlins, both scraping just above 650. Best in the NL: the 2009 Dodgers. And the fifth and final team to beat the league by 5% or more – indeed, second only to the 1939 Yankees at 105.52% – the 2001 Mariners, who tied the 1906 Cubs’ record of 116 regular season wins. The Mariners featured Ichiro, John Olerud, Bret Boone, Carlos Guillen, and yes, Mike Cameron in center again. They got some help from Safeco (home/road split of .300/.322), where they led the AL again in 2003 (Cameron’s last year there) and 2004.
Then there’s the 2007-08 Rays. As I noted before the 2008 season, Baseball Prospectus’ optimistic PECOTA projection for the Rays required them to massively improve on their MLB-worst team defense; as I noted that October, they did just that, to the point where nearly the entire turnaround to a pennant-winning team was a function of becoming the MLB’s best defensive team in one year. This made them just the ninth team ever to go worst-to-first in their league in DER in one year (other unsurprising names on that list include the Billyball A’s and the 1991 Braves), and aside from a team from 1878, Tampa’s defensive improvement was the largest leap of any of those teams, a 56-point or 8.6% improvement, which made their pitching staff much better without changing its personnel. The Rays did this returning five regulars – Carl Crawford, BJ Upton, Akinori Iwamura, Carlos Pena and Dioner Navarro – although Upton in 2007 was still learning center field as a new position, and Iwamura moved from third to second in 2008. Adding Evan Longoria and Jason Bartlett, plus clearing out some less mobile players and letting the incumbents settle in, led to a historic turnaround:

Team	Years	DER1	DER2	Change	Change %
CIN	1877-78	561	638	77	113.7%
TBR	2007-08	652	708	56	108.6%
CLV	1891-92	645	697	52	108.1%
PHI	1914-15	666	715	49	107.4%
OAK	1979-80	678	727	49	107.2%
BOS	1913-14	670	709	39	105.8%
ATL	1990-91	676	714	38	105.6%
WSH	1923-24	673	709	36	105.3%
NYY	1933-34	682	703	21	103.1%

National League

	BIP%	NL	High	DER	High %	Low	DER	Low %
2000	70.3%	689	CIN	702	101.89%	MON	672	97.53%
2001	70.4%	693	ARI	703	101.44%	MON	682	98.41%
2002	71.2%	695	LAD	716	103.02%	SDP	675	97.12%
2003	71.6%	694	SFG	710	102.31%	COL	678	97.69%
2004	71.2%	693	LAD	711	102.60%	COL	677	97.69%
2005	72.0%	693	HOU	705	101.73%	COL	670	96.68%
2006	71.2%	690	SDP	710	102.90%	PIT	674	97.68%
2007	71.5%	688	CHC	704	102.33%	FLA	659	95.78%
2008	70.5%	689	CHC	703	102.03%	CIN	671	97.39%
2009	70.2%	692	LAD	713	103.03%	HOU	677	97.83%

American League

	BIP%	AL	High	DER	High %	Low	DER	Low %
2000	71.7%	684	ANA	699	102.19%	TEX	667	97.51%
2001	72.3%	689	SEA	727	105.52%	CLE	670	97.24%
2002	72.4%	695	ANA	718	103.31%	CLE	674	96.98%
2003	73.2%	694	SEA	721	103.89%	TEX	674	97.12%
2004	72.1%	689	SEA	699	101.45%	KCR	674	97.82%
2005	73.5%	694	OAK	715	103.03%	KCR	666	95.97%
2006	72.6%	685	DET	701	102.34%	TBD	671	97.96%
2007	72.1%	684	BOS	704	102.92%	TBD	652	95.32%
2008	71.9%	688	TBR	708	102.91%	TEX	666	96.80%
2009	70.8%	688	SEA	712	103.49%	KCR	675	98.11%

The 2010s
History continues to march on: the NL in 2010 became the first league in baseball history to have less than 70% of all plate appearances result in a ball put in play.
2011 stats are through May 31, 2011. DERs can be volatile in-season; I noted a few weeks ago that the Astros were at 648, 633 around the beginning of May, which would have set them on pace as the first defensive team since the 1930 Phillies to finish below 650, but since replacing Angel Sanchez with Clint Barmes they’ve been on an upward trajectory, and are no longer even last in their division. As you can see, the Cubs are having a terrible defensive year, while the Braves and those Rays again (even sans Carl Crawford and Jason Bartlett) are flying high. The AL (unlike the NL) is above 700 this season, the first time either league has cracked 700 since 1992.
National League

	BIP%	NL	High	DER	High %	Low	DER	Low %
2010	69.7%	689	SFG	707	102.61%	PIT	671	97.39%
2011	70.2%	695	ATL	716	103.02%	CHC	665	95.68%

American League

	BIP%	AL	High	DER	High %	Low	DER	Low %
2010	71.4%	694	OAK	711	102.45%	KCR	679	97.84%
2011	71.6%	702	TBR	723	102.99%	CHW	691	98.43%

Part I here.