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# Probabilistic Model of Range and Center Field Defense

David Pinto has the 2007 figures for his Probabilistic Model of Range up for centerfielders.

What is PMR? Pinto explains, in a 2005 post:

I calculate the probability of a ball being turned into an out based on six parameters:

Direction of hit (a vector).
The type of hit (Fly, ground, line drive, bunt).
How hard the ball was hit (slow, medium, hard).
The park.
The handedness of the pitcher.
The handedness of the batter.
For each ball in play, the program sums the probability of that ball being turned into an out, and that gives us the expected outs.

So balls in play are lumped into different categories, and each category of BIP has, across major league baseball, an expected probability of being turned into an out. By comparing the BIPs for each player, and the probability of each BIP becoming an out, to the actual number of plays a player makes, one can evaluate whether a player is making as many plays as he'd be expected to make, which allows for an evaluation of his defensive performance.

Is it perfect? No. At least, I don't think it is. But I think this method gives you at least a decent idea of how players are performing, particularly when looked at in conjunction with some of the other advanced stats.

What jumped out at me on this list is that the #1 centerfielder (among players with at least 1000 BIPs) was Ranger trade target Coco Crisp. This isn't all that surprising to me, since Crisp's defensive performance this season, by just about every measure I've seen, has been top notch.

Ichiro, Felix Pie, and Curtis Granderson were 2-3-4 on the list, and again, that is consistent with their respective reputations.

GMJ came in at slightly above average, and surprisingly, Torii Hunter and Aaron Rowand at almost dead-even.

On the negative side, the Rangers had two guys in the bottom six, with Kenny Lofton checking in at 4th from the bottom, and Marlon Byrd at 6th from the bottom.

I've seen it suggested that it takes at least a couple of years of defensive data to really get a good picture for a player (because of the sample size issues), so I checked out the 2006 PMRs, as well.

Making a comparison, the data looks fairly consistent...Ichiro is 1st, Crisp is ranked high, Hunter and GMJ are in the middle, and Lofton is near the bottom. Interestingly, Grady Sizemore, who won a gold glove this year and who has a reputation for being a very good defensive centerfielder, ranked low both years, as well...

Anyway, I'd recommend checking out the lists, because there's some good stuff in there, and I'm going to follow up with some more PMR data for other positions tomorrow...but in the meantime, it makes me more encouraged about the idea of pursuing Crisp via trade this offseason...