Win Probability Scoring
As an alternative to ERV scoring, the Cheat's blog just did a White Sox game based on Win Probability Scoring - how much a particular player adds to a team's win probability by his performance. Here's the link. Although it's intriguing as a concept - and has been suggested by others - there are some data problems with WPA at this point. First, the data set for win probabilities may be a little off at this point. The data, as I understand it, is from 1979-1990. And, as it turns out, baseball has changed a little bit since 1990.
In addition, the WPA statistic is not terribly predictive in nature - a batter gets more WPA points if he hits a home run in the 9th inning of a 1-0 game than he does if he hits it in the 5th inning. In addition, I wonder how well it tracks the performance of a pitcher who pitches well but loses. It's interesting, and I think you'd be interested in reading the Cheat's scoring as well as the Hardball Times article linked.
posted by SuperNoVa @ 10:26 AM
7 comments
7 Comments:
Excellent post. I've been tinkering with a way to adjust the RV values we come up with for ERV scoring to reflect the impact on winning the game. I may post those figure up with the Friday Morning Figures someday soon.
Turns out under Win Prob Guzman still hurt us. We went from a 26 % chance of winning to a 14 % chance of winning with his sac fly.
Calculated using the
Win Expectancy Finder, which is certain to decrease my productivity today.
dexys_midnight: What inning is it in your example?
I think WPA is clearly a lousy measure for individual performance, but does it accurately predict a 2005 team's probability of winning a game? I don't see why not. Baseball isn't all that different now than it was in the '80s, is it?
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Here are some good links:
This one does a good job of explaining the strengths and weaknesses of Win Probability
http://www.hardballtimes.com/main/article/the-one-about-win-probability/
And the guy who did this one appears to have data from 1972-2002, but the page only shows one table for the start of each inning
http://www.livewild.org/bb/wintab.html
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