Thus, its not a big surprise to see Manny have the highest WPA of any Boston hitter over the last 15 years versus the Yanks. I’d bet Manny has the most PAs of any Boston hitter versus the Yanks over the last 15 years.

Ditto with Mo – no Yankee pitcher has faced the Sox more often with the game close or otherwise on the line.

Note too that on the top ten Red Sox hitters list, #10 is Sean Casey. The same Sean Casey who played all of 69 games for Boston in 2008 – and in that time, had all of 29 ABs against the Yanks. Leverage, baby.

The Sweeney-Ichiro example at the beginning shows, very simply, one of my biggest problems with WPA, but here’s a tidbit that will tug at all our heartstrings:

“Colin Wyers: Here’s more fun with WPA—the 1996 Yankees bullpen. Mariano Rivera, the setup man that season, has a 5.4 WPA. John Wetteland, the Yankees closer, has a 4.2 WPA.

At first blush, it makes no sense. Rivera pitched close to twice as many innings as Wetteland, had a lower ERA, higher K, drastically lower HR rate, a practical tie in walk rate-Rivera was much better than Wetteland, to an extent that WPA isn’t capturing.

The answer is leverage. Wetteland had a 2.37 aLI, compared to 1.54 for Rivera. Now, if we swapped out Rivera with an average setup man, Wetteland’s aLI, and thus his WPA, would drop. Wetteland, and not Rivera, gets all the credit for the extra leverage above average he is being provided by Rivera.”

WPA tells part of a story, but it leaves too much of that story out to be really useful for evaluating anything, AFAIC. As a snapshot of something though? Fascinating to look at.