http://www.baseballprospectus.com/articl...leid=21262

Well, I knew it varied, but I didn't know that so much info is mind numbing....

It would be interesting to see how the strike zone varies with score differential and inning. Anecdotally, it sure seems that the strike zone can get pretty small in the late innings.

There is one fundamental flaw in the methodology. The author says, "To assess the strike zone at the most granular level, I divided the plane at the front of home plate into 1x1 inch squares." But the strike zone is not simply the vertical plane at the front of home plate; it is the entire 3-dimensional solid above home plate (include all seven faces and all 15 edges of that solid). A pitch that misses the front plane but still catches some other portion of the solid is a completely valid strike, and not evidence of an expanding strike zone.

I don't know exactly how big the impact of this definitional flaw is -- maybe none at all. But the fact that the author doesn't acknowledge it (or even appear to be a aware of it) is a bit troubling.