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September 13, 2007

Schrodinger's Bat

The Return of the Fish Eye

by Dan Fox

"They both [statistics & bikinis] show a lot, but not everything."
--Infielder Toby Harrah

Last week in this space we updated our projection of Nationals slugging outfielder Wily Mo Pena. In doing so, we noted anecdotally the difficulty that Pena has had in laying off of pitches out of the strike zone, particularly from right-handers. As we discussed in a previous column, the wealth of data provided by PITCHf/x now allows us to quantify just to what extent our analysis of Pena--or any player for that matter--is on track. So today we'll hail the return of the "Fish Eye" as we update our look at plate discipline.

Revealing a Little More

For those who missed our last installment on this topic, we'll bring you up to speed. Using the location data provided by PITCHf/x (plotted as the pitch reaches the front of home plate), combined with the customized strike zone provided for each plate appearance, we can get a pretty good idea of whether a pitch offered at by a hitter would have been within the regulation strike zone. Likewise, if the hitter did not swing at a pitch that should have been called a strike, we can note that as well. By adding up the "balls" that were swung at, the "strikes" that weren't, and everything in between (as well as making a few adjustments for the count along the way) we can create new metrics that collectively give us a picture of what has traditionally been termed plate discipline.

Although in our previous analyses of umpires we've used a buffer zone to give them the benefit of the doubt, here we do not; we simply use the standard 17-inch-wide plate, along with the actual height customized for the player.