I recently became fascinated with the strike zone and its effective boundaries. The strike zone laid out in baseball’s rule book is simple; it extends a total of 17 inches across the width of home plate, between the hitter’s knee and midsection and covering the entire depth of the plate. The strike zone as it actually gets called by umpires is complex. It shifts quite significantly depending on the handedness of the hitter for one.
That’s not the whole story though, not even close. The dexterity of the hitter isn’t the only significant variable in how the strike zone is called. Compare the following two strike zone heat maps, fitted from 2012 data on called pitches to right-handed hitters.