Friday, July 18, 2014
wOBA Intro
?Good job by Neil in describing wOBA. A few of my responses:
IBB issue:
Suppose you calculate wOBA as has been described, and your player ends up with a wOBA of .320.
Now, suppose that you insist on including IBB. We agree it shouldn’t have the full weight of a walk (.70), but we also agree it’s better than an out (.00). Assume that the weight for the IBB is .32.
What happens to this player’s new wOBA if we include IBB in both the numerator (with the .32 weight) and the denominator (as a full PA)? Nothing! His new wOBA stays exactly at .320.
And if you think about it, what wOBA implicitly does with the IBB is to give it a DYNAMIC weight that is exactly equal to the hitter’s wOBA. So, Bonds’ IBB is worth .50 while the #8 hitter’s IBB is worth .25.
And it makes perfect sense if the IBB is win-neutral with respect to the hitter at the plate.
***
HBP v UBB:
As has been noted, HBP occurs more often when it can do more damage than the UBB, namely with a runner on 1B. UBB are issued disproportionately with 1B open.
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ROE issue:
When the defense gets an error, this is a BAD thing for the defense. You can argue it’s far more bad for the fielder than the pitcher, but nonetheless, taking the defense together as a whole, it’s bad for the defense to allow a runner to reach base on error.
And for the defense, whether they allow a runner to reach base on error or by a single, it’s a similar kind of damage.
Defense is pitching+fielding.
Since offense is the exact mirror of defense, whatever is bad for the defense is good for the offense. Regardless of the amount of talent it takes for the batter to reach base via error or via hit batter, the fact is the offense BENEFITS.
***
"Making an out doesn’t change his wOBA, except for the slight increase in PA."
EXCEPT? That's a huge exception! Take for example a hitter with a .320 wOBA on 600 PA. That would mean he has "192" in the numerator and 600 in the denominator.
Now, give this player 20 walks. That adds 14 to the numerator (now at 206) and 20 to the denominator (now at 620). His wOBA is now .332.
Now, give him 24 outs. Numerator stays at 206 and denominator at 644. wOBA is .320.
So, adding 20 walks has been cancelled out by adding 24 outs.
And that's perfectly fine.
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