Tuesday, August 9, 2011
More on Run Differentials
Last week I looked at the Yankees’ run differential and made the point that actual runs scored and allowed can be a bit misleading, and that it’s probably more instructive to look at the context neutral value of the offensive events for and against a team to get a better sense of how good they have actually been. For the hell of it I decided to look at this for all teams in MLB as of this morning.
|Team||RS||RA||bRS||bRA||RS - bRS||RA - bRA||Gap|
RS/RA: Actual runs scored/allowed
bRS/bRA linear weights batting runs scored/allowed.
Gap: RS - bRS minus RA - bRA. The larger the number, the more a team has outplayed their peripherals. Basically, positive is bad here and negative is good.
What this table is saying is that, for example, the Yankees have scored about 26 more runs and allowed 19 fewer runs than their peripheral stats say they should have. That doesn’t mean you should subtract 4.5 wins from their total on the season. It just means that their Pythagenpat record/run differential is a bit misleading. In the Yankees’ case they’ve got 73 Pythag wins and 69 actual wins, so they haven’t really taken advantage of this in actual wins.
Contrast that with Pittsburgh, who’ve stumbled lately. They were playing over their heads all year, and unfortunately the correction has been ugly. At 55-59, they’re still two wins ahead of their 53-61 Pythag record, and if you look at that gap they are probably not even that good.
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