Wednesday, June 13, 2007

Zambrano and Barrett

There have been discussions in the media regarding Carlos Zambrano, pitcher for the Cubs, and his relative performance when Michael Barrett is the catcher compared to other catchers. So far this year, Zambrano is 2-4 with a 7.50 ERA when Barrett is catching, and 5-1 with a 2.64 ERA with other catchers (these statistics were reported on Pardon the Interruption yesterday). The media has been trying to come up with answers on the difference in the Zambrano's performance. Maybe the two players just don't get along. Maybe Barrett is too head-strong and is calling pitches that Zambrano doesn't want to throw. They quoted Koyie Hill (a back-up catcher for the Cubs) that he just let Zambrano throw what he wanted when Zambrano pitched 8 innings and only gave up 1 run. This implied that Barrett didn't and that it was Barrett's fault that Zambrano pitched so poorly. It is possible that one of those explanations is the reason, but there is another reason that the media seem to never bring up as a possible answer: randomness.

There are a lot of random things in sports. Sometimes a pitcher pitches well and still gives up a few runs. Sometimes a pitcher just pitches ok, but sneaks by with a shutout. Could the difference in Zambrano's performance with different catchers be due to randomness? Yes, it could be. What was Zambrano's record when Barrett caught him in 2006? What about 2005? Without even looking at the statistics, I'd be fairly comfortable guessing Zambrano did not do perceivably worse with Barrett in past years because the media didn't say anything about that! The media uses the same "lets make our argument look better by not providing all the facts" strategy that some touts use when they say they were 9-2 in their last 11 games.

If given the chance to make the wager, I would be willing to bet that it is due to randomness. How would one implement that bet? The only way I know how is if the betting line reflects poorly on Zambrano and the Cubs the next time Barrett is known to catch Zambrano. If the media hypes it up more and bettors start to believe it, maybe the line will be skewed enough for a wager on Zambrano to make sense. I don't think this will happen, I think the betting lines will assume the catcher is not a big factor. But I think it is useful to prepare for that possibility if it does happen.