Saturday, October 1, 2011

Do Diamondbacks have stats to match Brewers stars?

Click here to read the AP article by Chris Jenkins. He writes:

"The Diamondbacks might not have the Brewers’ marquee names. But the numbers, and the results, show two teams that are surprisingly similar going into Saturday’s Game 1 of the NL division series."

This sounds like an interesting question yet very few numbers are presented in the article. Actually no numbers that statistically compare the two teams. It turns out, that by luck, the Diamondbacks over achieved with runners on base, a trend that no team can keep up.

It looks like the Brewers are much better. Their hitters had an OPS of .750 while their pitchers allowed a .689. That gives them a differential of .061.

The Diamondbacks hitters had an OPS of .736 while their pitchers allowed a .725 OPS. That gives them a differential of .011. Well below the Brewers.

Based on some regression analysis I have done, we can project winning pct with the following equation:

Pct = .5 + 1.3*OPSDIFF

This gives the Brewers a pct of .579 or 93.85 wins. The Diamondbacks get .514 or about 83.32 wins. This seems like a very big difference.

Yet the Brewers actually only won 2 more games (96 vs. 94). And the Brewers runs differential (721 - 638 = 83) is only slightly higher than the Diamondbacks run differential of 69 (731 - 662).

What allowed the Diamondbacks to match the Brewers, at least on the surface? Some very good luck. They over achieved with runners on base. The Diamondback hitters had an OPS of .770 with runners on base (ROB) while their pitchers allowed .731. That gives them a differential of .039.

The Brewer hitters had an OPS with ROB of .745 while their pitchers allowed .719 for a differential of .026.

This seems to be something in favor of the Diamondbacks, but it really isn't.

Doing better with runners on base will improve your chances of winning. You will score more runs than expected and give up fewer runs than expected. Yet, in the long-run, individual players and pitchers (and teams) end up performing about the same in clutch situations (like ROB) as they do overall. Even the best clutch hitters and pitchers do just a little bit better in any clutch situation than they normally do given a large enough number of games.

For the Diamondbacks to to even look like they are as good as the Brewers, they had to be lucky. We cannot expect them to continue to over achieve so much with runners on base.

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