Posted by: Peter | August 6, 2010

Did that umpire really screw Jesse Crain?

Yesterday’s game was certainly the strangest Twins game I’ve seen in a while. Kubel’s game-winning catwalk pop-up would have been odd enough, especially coming right after a 6-run Rays comeback. But on top of all that, there was Jesse Crain’s face-off with Willy Aybar, which ended in a bases loaded walk. Over at Twinkie Town, they’re up in arms about that at-bat, because it appears that home plate umpire Chris Guccione was totally unwilling to call a strike, even on balls that appeared to be in the middle of the strike zone:

That sure looks bad, but when I saw it I was a little suspicious. To see whether this was really as egregious as it looks, we need to put these pitches in context. Yes, it’s true that two of those pitches were called balls even though they were pretty clearly within the rulebook-defined strike zone. But as John Walsh showed in a seminal analysis, umpires don’t call the rulebook strike zone. Not only is the “empirical” strike zone different from the rulebook one, it’s also different for right- and left-handed hitters! So just observing that the umpire wasn’t calling the rulebook zone isn’t that remarkable. What we really want to know is whether he was calling a consistent zone. So those pitches by Crain really need to be put in the context of all the pitches that were called in the game, split up by right- and left-handed hitters  (click the image to expand):

You can see those two questionable balls from Crain on the right-hand side. Only now they don’t look quite as questionable. Relative to the zone Guccione had been calling throughout the game, they were really borderline pitches, because the up-and-in pitch to left-handers hadn’t been called a strike all day.

As a Twins fan, I’d love to be able to tell a story about an incompetent ump screwing the Twins over, and the baseball gods setting things right through the power of the catwalk. And before I did this analysis, that’s basically what I thought had gone down. Unfortunately, the evidence just doesn’t back that up. It just goes to show how easy it is to misinterpret evidence when you have a strong motivation to fit it into your pre-conceived worldview.


Responses

  1. [...] Several bloggers across the Twins Nation have taken note see their articles: Unlucky Jesse or “Empirical” strike zone.   Whatever the case, Jesse Crain has given up one earned run since June 10. A stretch of 20 [...]

  2. [...] is complaining about umpire Mike DiMuro’s strike calls in yesterday’s game. After my last post, I was prepared to make yet another post on rulebook-versus-true strike zones and the bias of fans. [...]


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