Thursday, March 09, 2023
Get ready for stolen bases in 2023
While most presentations of the new rules is strictly about the rules themselves, the consequences of those rules are not discussed very much as it pertains to stolen bases. The intended consequence of the new rules, notably the limited number of pickoffs, is that it frees up the running game. And given what we've seen in the minors, and what's happened in spring training so far, we will get that impact in 2023.
In Spring Training 2007, the number of stolen base attempts of 2B was at 1.68, which was down from 2006 at 1.74. Not coincidentally, the SB success rate went up from 66% to 70%. This pattern repeated itself in 2008: SB attempts went back up to 1.75 (similar to 2006), while SB success rate went down to 67% (also similar to 2006). And most of seasons, this yo-yo effect continued.
Why would this happen? Well, when you are aggressive, the number of SB attempts goes up. But being overly aggressive also means you are taking extra chances, running in scenarios where the likely success rate is fairly low.
You can especially see the pattern from 2017 to 2022, as every season the SB attempts went down from the previous year, from 1.66 attempts per game in 2017, down to 1.31 in 2022. And we had an almost perfect matching of the SB success rate going up almost every season, from 67% in 2017 to 73% in 2021-22. So, the more you pick your spots, the fewer the attempts, but the more successful you will be when you finally do run. There's a tradeoff that happens.
2023 changes all of that. Big time. Because of the new pickoff rule, SB attempts have skyrocketed to 2.01 per game, more than 50% higher than in 2022. Are the runners being insanely aggressive? No. They are taking advantage of the new Pitch Timer rule, which limits the number of disengagements (read: pickoff attempts) the pitcher has. Knowing the pitcher has limitations, the runners are attempting more steals, likely with somewhat larger leads. And the result is a an enormous jump in SB success rate: Whereas we were at 73% in 2021-22, we are now over 80% in 2023.
Let me show it to you in chart form, so you can really appreciate the difference (click to embiggen). The blue line is the number of SB attempts per game (both teams), while the dotted orange line is the SB success rate.
In addition to the SB, regular balks are also way up. And while pickoffs are up slightly, most of that gain for the pitcher is given back with the new forced balks (balks awarded due to the violation of the new rule, what I call Stolen Balks). In the next chart, I plot all the positive baserunning events (steals, balks, errant pitches, defensive indifference) on the x-axis, and the negative events (caught stealing, pickoffs) on the y-axis.
Focus on 2018 through 2022: as the number of positive events goes down, so too does the number of negative events. 2023 throws all that out the window. We have as many negative events in 2023 as we did in 2021-22, but the number of positive events is up by 1 per game. In other words: a free base at no cost, once per game (or 0.5 for each team per game).
As players adjust to the new environment, expect the success rate to continue to go down while the steal attempts continue to go up. We should be reaching a breakeven point at the league level of 75% success rate. Essentially, SB should be attempted whenever the breakeven point is at least 70%, and therefore, the average of the steals above this line should likely come in at around 75%. Whether it takes under a season or multiple season for players to adjust, we will soon learn.
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