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Wednesday, March 21, 2007


David Appelman, operator of FanGraphs, recently announced the addition of play-by-play summaries of all ballgames from 2002-2006 on his site. What makes this noteworthy is that he has added WPA (Win Probability Added--think of it as measuring the instantaneous shifts in the chances of winning a game with each play) statistics to each play, allowing you to see, at a level of detail that we've never had before, how each individual play in each game affected the chances that a given team would win or lose. Here's a screenshot I just took from his site featuring the ninth inning of one of the best Reds games last September:
Note the fifth play of the ninth inning involving the newest Reds right fielder. :) It was his last at-bat of the season, as a pinch hitter, in the final home game of the season.

I've posted the WPA graph from this game previously, and I think that the graphical output is still the most intuitive way to understand what win probability statistics do for us. But I'm very excited to have the chance to dig into games now and then and identify just how "huge" a particular strikeout is in a given situation. :) And best of all, fangraphs is planning to release this play by play data live this season, so that we can follow along as things happen. Should be fun.