Saturday, March 26, 2011

Umpire Strike Call Percent, In and Out of Rulebook Zone

I've finished up some preliminary tabulations for umpire calls within and outside the rulebook zone. Because it's a fairly large table, I'm not going to present it directly on this page. However, you can download the file here.

Keep in mind that these are based on the rulebook zone. The numbers say nothing but how well the umpires conform to their own zone. Umpires tend to have their own zone, which are likely well-known by the players in the game. Some zones are shifted outside, most stretch a bit beyond the edges of the plate, and so on. Combining these numbers with the visuals in my previous post are your best bet for understanding where the "Incorrect" calls are coming from. Most likely, these are just outside the book zone but within the 2-foot wide zone.

We really don't know WHY the zone tends to extend beyond the plate for umpires (well, maybe someone does, I don't know though). One suggestion is that Pitch F/X measures the center of the ball, so there is 1.5 inch worth of ball on either side. That extends the zone 1.5 inches beyond the plate on each side assuming an umpire calls a strike if ANY portion of the ball touches the black.

The rest of it could simply be a perception issue. The ump looks from the center of the plate toward the outside of the plate. Because anything on the corners is viewed at an angle, the umpire makes some sort of guess based on visual cues as to whether it went directly over the plate (they don't have a perfect bird's eye view of every pitch). The question then becomes: how should we evaluate them? The book zone, or a predictable zone for each umpire? I'll leave that question for another day and for someone else to answer.

There is a separate worksheet for each year (2007 to 2010). I might add some other info in the next couple days to the file like # of pitches within and outside the zone, and counts of each designation in the file. There are some extra umpires in the file with no data, and many of these are guys that got some assignments in spring training. The data should be only regular season games. Lastly, keep in mind that the correctly called balls and incorrectly called strikes do not add up to 100%. This is because I left out Pitch Outs and Intentional Balls from the cross-tabulations.

If you use them for any write ups anywhere, I appreciate a cite or link back. At the least just let me know, because I'd like to see what people do with the data just for my own curiosity.

UPDATE: DATA IS NOW AVAILABLE HERE.

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