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Michael/Male/26-30. Lives in United States/Pennsylvania/Wexford/Christopher Wren, speaks English. Spends 20% of daytime online. Uses a Fast (128k-512k) connection. And likes baseball /politics.
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United States, Pennsylvania, Wexford, Christopher Wren, English, Michael, Male, 26-30, baseball , politics.

Thursday, February 10, 2005

Thoughts on PMR 

I know it's been a heck of a couple of weeks thanks to the Eagles near-successful run at football immortality, but it's time to get back to baseball.

Dave Pinto of Baseball Musings recently worked out a new way of looking at team defense by introducing “Probabilistic Model of Range” (PMR), a process by which he broke down balls put into play and their expected outcomes. The expected outcomes flow from six factors: 1) direction of the hit, 2) type of hit (bunt, flyball, etc), 3) how hard the ball was hit, 4) the park, 5) the pitcher, and 6) the batter. The idea Dave came up with is to compare the expected outcomes with the probable outcomes, and rank the teams based on how they did. If a team did better than expected, the better defense they have.

The results and his whole post are here, but I’ll share a little of the results: the five teams that beat their expected DERs were the Cardinals (.0032 better), the Red Sox (.0027 better), the Cubs (.0031 better), and the White Sox (.0019 better). The Phillies were fifth, .0003 above their expected DER. Interestingly, the worst teams were the Yankees (.0176 behind), the Tigers (.0181), the Royals (.0208 behind) and the Angels of Anaheim, Los Angeles, California, whatever (.0209 behind).

I like Dave’s work, and I like his methodology, but any result that comes back and tells me that the Boston Red Sox were the third-best defensive unit in baseball last year makes me raise my eyebrows. I see the data, I don’t dislike the method it was created by, but I simply don’t think it’s true. My eyes and the numbers tell me that it is wrong:

I’ll start with the weakest part of my argument: I watched a number of Red Sox games in 2004 and I can’t believe that was the third-best defensive team in baseball. Even after the July deals which sent Nomar to Chicago, I don’t think this was a great defensive team. They played good defense, solid defense, but any team with Manny Ramirez in the field can’t be called “strong” defensively. They missed balls, dropped flys, displayed hits and sometimes played defense like my little league team did. Second best defensive team?

I’ll buttress my argument with some numbers. Here are the MLB ranks on the major team defense stats for the Red Sox:

Fielding Percentage: .981, 23rd in MLB
Range Factor: 37.23, 17th in MLB
Zone Rating: .829, 30th in MLB
Errors committed: 118, 25th in MLB

Not one finish in the top half and, aside from range factor, the Red Sox ranked in the bottom ten on all of these stats. Zone Rating, which is the one I put the most faith in, ranked them dead last. Great defensive team? I simply don’t believe it.

That said, I can’t disagree with a lot of Dave’s conclusions: he ranks teams high that I’d rate high. Cardinals are the best defensive team in baseball? Why not? They were #2 in MLB ZR. The Dodgers and Phillies were Nos. 7 & 5 on Dave’s list and they committed the fewest errors in 2004. The Dodgers actually had the highest ZR in the MLB.

I could be wrong. The Red Sox could just be an anomaly, a glitch. I find Dave’s work interesting, but I’m skeptical. That said, he’s given us a valuable resource. Check out his work when you get a chance.

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