During the Tigers-Red Sox game last night, Tim McCarver said he thought it was a little odd that the Tigers would bring in lefty Drew Smyly to face David Ortiz while also leaving the shift on, since lefties are more likely to go to the opposite field against a left-handed pitcher. (At the very least, I know he said this last part. Memory is a tricky thing, and I’m now not sure whether he said this about Ortiz or someone else, possibly Alex Avila.) Being Tim McCarver, he didn’t say why this might be true, nor did he cite a source for this information, putting this firmly in the realm of obnoxious hypotheses.
The first question is whether or not this is true. For that, there are these handy aggregated spray charts, courtesy Brooks Baseball.
Based on these data, I have to say it seems like McCarver’s assertion is true: they are slightly more likely to go to left against a left-handed pitcher. I don’t have enough information to say if the differences are either statistically significant (I’d guess it is, given the number of balls these guys have put into play in the last 5-7 years) or practically significant (I kinda doubt it). Regardless of the answer, though, the fact remains that the appropriate thing to do is to bring in the lefty and shift slightly less drastically, so who knows why McCarver brought this up to begin with. After all, Ortiz hits drastically worse against lefties (his OPS against lefties is 24% smaller than his lifetime rate, via baseball-reference), as does Avila (36%).
There’s also the question of why this might be true, and in fairness to McCarver, there are some pretty plausible mechanisms for what he was saying. One is that a breaking pitch from a left-hander is more likely to be on the outer part of the plate for a left-handed batter than a similar pitch from a right-handed batter, and outside pitches are more likely to get hit the other way. Another is that left-handed batters can’t pick up a pitch as easily against a left-handed pitcher, so they are more likely to make late contact, which is in turn more likely to go to the opposite field. I can’t necessarily confirm either of these mechanisms empirically, though looking at Brooks splits for Avila and Ortiz suggests that the fraction of outside pitches they see against left-handers is about 3 percentage points larger than the fraction against righties.
So, what McCarver said was true (though not terribly helpful), and there are seemingly good reasons for it to be true. I still posted something, though, because this is a great example of something that pisses me off about sports commentators–a tendency to toss out suppositions and not bother with supporting or explaining them. (Another good example of this is Hawk Harrelson.) That tendency, along with their love of throwing out hypotheses that are totally unfalsifiable (McCarver asserting that the pitching coach coming out to the mound is valuable, e.g.), is one of the things I plan to deal with pretty regularly in this space.
(Happy first post, everyone.)