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Wednesday, September 07, 2011
Where do umpires position themselves?
Wonderful charts here. Here’s one of them. The “in” and “out” designation is where the catcher is positioned. So we see that the umpire is influenced not only by the batter’s handedness, but also by the position of the catcher. Mike shows the charts of two other umpires, and you can see that umpires are like snowflakes.
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He also points out some anomolous PITCHf/x call.
I would like to touch on one other aspect of umpire strike zone evaluation. If you look closely at Estabrook’s plot for right-handed batters, you may notice something strange. Did he really call a strike on that pitch located at 2.96 feet high and 1.87 feet wide of the center of the plate? That is 14 inches off the edge of the plate!
If you believe the PITCHf/x data, then yes, he did, but it might be wiser to believe Estabrook than the data in this case. I reviewed the video of that pitch, and while it does appear to have been outside off the plate, it almost certainly was not 14 inches outside. By no means do I advocate video as an accurate method for judging strike calls. Relying on video leads to all sorts of problems, not least not being able to tell when the ball crossed the plate, even with a straight center-field camera view as we have for the pitch in question here. With those caveats, here is a still frame showing roughly where the ball crossed the plate. From this angle, the pitch appears to be maybe five inches outside.
Sometimes you get calibration issues, and when technology misses, it misses big. A good example is if you track hit locations of minor league parks. It’s obvious that one park is hugely shifted. MLBAM assures me that all the parks work off the same software, but every year I’ve done this, this one park is hugely off. While most home plates are in the vicinity of x,y = 125, 200 pixels, this one park is more like 165, 230.
The real problem with the calibration on PITCHf/x is that they may not be consistent game to game, or even within game possibly. So, what should be systematic biases (which can be easily corrected through post-game analysis) ends up looking like possibly random biases. Knowing that all games are at 165, 230 is more beneficial to me than MLBAM tinkering with the software mid-season to try to get it right (which they haven’t done since last time I checked).
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