Sox Watch

Friday, April 28, 2006

Red Sox WPA through 4/27

This one was over before it started. Beckett gave up -0.267 in WPA in the first inning, and that was all the Indians really needed, since the Sox offense has apparently decided not to come along for this road trip. Manny's eighth-inning homer on Tuesday was the only thing preventing the first sweep of the season.

Individual Player WPA Contributions
Thursday, 4/27/06
Red Sox 3, Indians 15

Full-Season Player WPA Contributions
Through Thursday, 4/27/06

Full-Season Category WPA Contributions
Through Thursday, 4/27/06


  • Thanks, Sox Scout. This is outstanding work, and despite the lack of comments much appreciated, no doubt by many. You have been cited on Sons of Sam Horn!

    Since you are keeping cumulative stats for the Red Sox players, is there any relation between the sum of the individual cumulative stats and the Sox record as of that date? That is, if the Sox are 2 games over .500, should the sum of the individual WPAs be 2?

    The Sox bullpen has been better than I would have guessed, though obviously heavily influenced by Paps and Foulke.

    Thanks again from Colorado.

    By Anonymous SoxFanCo, at 1:49 PM  

  • Thanks for the comments, soxfanco.

    You're exactly right about the concept of cumulative totals, although your specific example is off by a factor of 2.

    In every game the team plays, the Win Probability starts off at 0.5 (there is a fifty-fifty chance of winning and losing, ignoring disparities between the teams and home field advantage). At the end of every game, the Win Probability is either 0.0 (they lost), or 1.0 (they won). So in each game, the total cumulative Win Probability either goes up by 0.5 (in a game they win), or goes down by 0.5 (in a game they lose).

    So currently, the Sox are 4 games over .500, which means that their total cumulative team WPA for the season is exactly 2.000.

    If you've been following the WPA discussion on Sons of Sam Horn, note that the stats calculated there by BosoxBob are actually multiplied by 2 to ensure that the cumulative total goes up or down by exactly 1.0 in each game.

    By Blogger jpo, at 2:08 PM  

  • Thanks for the explanation. Sometimes I can be really dense, but you cut right through it!

    I'd argue that the chances of winning are more like .90/.10 vs KC. The bookies recognize this; why not sabremetricians? (this paragraph was written tongue in cheek)

    By Anonymous soxfanco, at 3:29 PM  

  • That's actually a very good point, soxfanco. I would love to be able to take team disparities into account when calculating WPA, but I don't have a good statistical framework for doing this yet. Perhaps later in the season we can start to get more sophisticated, to distinguish between a Yankees game and a Royals game, or home vs. away. Thanks for your comments.

    By Blogger jpo, at 8:58 AM  

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