Layering the PITCHf/x Leaderboards

Continuing my series (Part 1) looking at detailed pitcher stats made possible by PITCHf/x data, today I'm going to look at RV100 data by strike zone layer.  Remember, RV100 stands for Run Value per 100 pitches and is compared to average.

What's a layer?  

Think of the strike zone and surrounding space as a cake.  Chocolate cake, angel food cake, whatever kind of cake you like.  When you move between layers of a cake, you move up and down. That's opposed to slices of a cake, where you move side to side between slices.  Layers pay no regard to the lateral location of the pitch, and slices ignore the vertical location.  Here's a diagram for the five layers I use:

"Middle" pitches are the middle third of a hitter's strike zone. "Up" and "Down" are the top and bottom thirds of the strike zone, respectively, creating three equal layers. "High" and "Low" are above and below the strike zone, respectively.

The overall top and bottom of the strike zone for each hitter is defined by the average values across all plate appearances by that hitter.  Aggregating their zones evens out oddities that arise from the top and bottom boundaries being manually set by human PITCHf/x operators.

Here are the baseline RV100 numbers for each layer, found by combining all PITCHf/x data going back to 2006.  I mean everything, including the WBC, Futures Games, Exhibition, Playoffs and Regular Season. Lower numbers are better for pitchers.

High    1.84
Up     -2.46
Middle -2.75
Down   -1.76
Low     1.79

Here are the best and worst pitchers by strike zone layer, based on 2009 regular season games through May 14.  A minimum 71 pitches was needed to qualify for a layer.