Studeman: 10 lessons I have learned about Win Probability Added

From SABR member Dave Studeman at The Hardball Times on April 29, 2014:

Ten years ago, I wrote an article called The One About Win Probability (Friends was a big hit on TV at the time), and it has turned out to be the most-read article in THT’s history. I’ve written about Win Probability many times since, most notably every year in the Hardball Times Annual, and I’ve learned a few things about WPA along the way. Allow me to share.

Lesson #1: Win Probability Graphs are Cool

The box score is perhaps the most beautiful display of data in the known universe. It contains so much terrific information in a compact space. But it lacks one thing: the dynamic of the game. Box score information is static, but games happen in real time.

Exhibiting runs scored by inning helps capture the dynamic of individual innings, and Game-Winning RBIs helped capture the dynamic of individual hits (which, I think, was the primary appeal of that otherwise irrelevant stat). But WPA graphs are much better at capturing the dynamics of the total game. They are a natural accompaniment to the box score.

The above graph is from a game played on April 23 this year, when the Angels had a 4-1 lead on the Nats in the ninth inning. Their biggest hit had been Albert Pujols’ double in the top of the sixth. But thanks primarily to Jayson Werth’s double and then Adam LaRoche’s single, the Nats staged a statistically improbable comeback in the ninth to win the game, 5-4.

Everything I just told you came from looking at the graph. If you hold your mouse over any point in the game, you’ll see much more … exactly what happened on each play and how much it impacted the game. If you had perused just the box score, you might have missed what made this game special.

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Originally published: April 29, 2014. Last Updated: April 29, 2014.