Carruth: The size of the strike zone by count

From Matthew Carruth at FanGraphs on December 18, 2012:

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.


Strike zones in 3-0 counts are called over a larger area than in 0-2 counts. That is neither new nor surprising information. What I wanted to do was get more specific though and so I broke apart the 2012 data sample by both hitter side and count, fitted strike zones to each of the 24 categories and then computed the area of the zone, in square feet, created by the 50% threshold.

Read the full article here:

Originally published: December 18, 2012. Last Updated: December 18, 2012.