WPA Usage

October 02, 2006

A couple of tidbits to fill your day waiting for the playoffs to start.

Nate Silver has introduced a new stat at Baseball Prospectus called Secret Sauce.  It combines those elements Nate and Dayn Perry found have the most impact on postseason success: fielding, strikeouts and bullpen.  It’s an interesting stat, but I found it disconcerting that Nate used WXRL (closer only) for his bullpen measurement.

WXRL is Baseball Prospectus’s version of WPA.  As always, care should be taken when interpreting WPA and I don’t think Nate gets it quite right.  In this case, WXRL includes both the performance of the ace and the number of close situations he was brought into.  Closers have no impact on the criticality of their appearances—that is totally up to the manager.  I don’t understand why Nate would include it.

Now, Nate might say that WXRL came out well in his regression analysis, but that wouldn’t be a good response.  Even though a variable may work well in a regression analysis, that’s not a good reason to include it in a formula.  There needs to be a logical rationale for why it should be included.  I don’t see the logic behind using WXRL.

On another note, the Wall Street Journal ran an article last Friday (by Sam Walker, who mentioned our site in his book Fantasyland) that ranked the clutchiness of all postseason plays.  Guess what they found to be the biggest clutch hit?  Tony Womacks’ game-tying double against Mariano Rivera in the bottom of the ninth, Game Seven, 2001.  The one before Luis Gonzalez’s game-winning hit.  Yes, that was deemed even clutchier than Bill Mazeroski’s home run against the Yankees in 1960.

It’s an interesting read, and Walker is to commended for using WPA as the baseline for his analysis.  Unfortunately, he included several other elements in his analysis.  Actually, the elements (quality of the pitcher, impact on probability of winning the series and not just the game) were good, but the approach was kludgy.

Oh well.  Still an interesting read.  Here’s the link, though I think you need to be a subscriber to read it.  Hat tip, JP.



Name:

Submit the word you see below:


 
<<Previous Article:  The Win Expectancy Contraption Next Article:  WPA Curiosities>>