Pitch Framing Newsbeat
Monday, March 03, 2014
Rather than identifying a single strike zone and giving binary credit for each pitch relative to that strike zone’s borders (i.e., strike or no strike), our model gives partial credit for each pitch based on that pitch’s likelihood of being called a ball or a strike. To determine that, we created a probability map of likely calls… To reflect what is best known about the way the size and position of the strike zone shifts from count to count and batter to batter, we ran individual models for each set of batter and pitcher handedness as well as [type of pitch]. The smoothing parameters of each model were allowed to vary by count, so that while the general shape of the strike zone derived for each variable combination did not change, the width and height of it did (reflecting, for example, a larger strike zone on 3-0 counts than on 1-2 or 0-2 counts). We also accounted for the changing size of the strike zone from season to season (although these yearly changes are much smaller than the other changes we measured).
We also corrected the data in several ways before running these models. First, all pitch classifications were hand-labeled by Pitch Info to eliminate variability in pitch labels… To account for batter height differences, we normalized the height of each pitch by the batter’s height using what is now the standard formula (first published by Mike Fast). We also used the correction scheme that Mike published at BP for correcting the X and Y location of each pitch based on the likely distribution of pitch locations that each pitcher would use against left-handed hitters and right-handed hitters…
Rather than simply give a single credit for each pitch (~.14 runs) as has been done in many previous models, we looked at the count in which each pitch was framed and gave credit equal to the difference in runs between framing or not framing that pitch. For example, a frame in an 0-2 count was counted as more valuable than a frame in an 0-0 count, because a frame in an 0-2 count can result in a large change in run expectancy while a frame in an 0-0 count does not have quite the same impact… The run value for a framed pitch is the run value differential for that count… multiplied by the residual of the probability—in other words, if an 0-0 pitch is called a strike in a spot where it’s normally called a strike just 80 percent of the time, the catcher will get 20 percent of the available value (.08) for a total of .0004 runs credited (which will later be adjusted based on the pitcher and umpire impact). Failing to get a strike on the same pitch would result in a .0016 run deduction…
We empirically determined each pitcher’s value—to isolate it from each catcher’s value—by performing a WOWY (“With or Without You”) analysis… We also made systematic but small changes to the data based on the umpire who was calling each game…
we have regressed career totals to the league average… Because seasonal variability is different from career variability, we also regressed seasonal totals to career totals based on a similar formula…
You can find all of this new framing and blocking information in a couple place on the Baseball Prospectus site.
Friday, February 28, 2014
I often discuss pitch framing with my colleagues. The most common source of doubt I hear: The numbers don’t pass the sniff test. The infamous Jose Molina has too many smart people crinkling their brows. This is a determination each of us has to make. Can there be a possible 5-win data inefficiency that existed for 100-plus years of baseball history? Can it be possible such a big deal was missed for so long?
We have to ask ourselves: How important is pitch framing and receiving? How important can it be?
Good summary and reference.
for his generous support.
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