WPA: next big thing?

I’m a fan of win probability added

Now, just from this example, a few of Win Probability’s cool features are clear. For one, we can use WPA to identify the most critical plays in any game. As it turns out, Jackson’s punt return had by far the highest WPA of any play in that Eagles-Giants game. For another, in every contest, the players on both teams have a total of exactly one WPA to divvy up. That’s because both teams start with a 50 percent chance of winning (or 0.5 wins), with one moving to 100 percent at game’s end (one win) and the other to 0 percent (zero wins). In fact, WPA is actually measured in wins: Jackson’s clinching TD was worth 0.46 wins to the Eagles. So by adding up a player’s WPA over a season or career, we can get a handy snapshot of which players are truly most valuable. For example, through Week 15, Falcons QB Matt Ryan was leading the NFL with 4.43 WPA.

But the best thing about Win Probability is that it captures, like no other stat, how we viscerally experience sports. As fans, we carry in our guts a reflexive, fuzzy calculation of our team’s chances of winning a game — a nervous tension that explodes after triumphant plays and collapses after moments of agony. Win Probability expresses that emotion with mathematical precision. Throughout the fourth quarter of that Eagles-Giants contest, Win Probability showed what New York fans felt: An all-but sure thing (the Giants had a 99 percemt Win Probability when they took a 21-point lead with 8:17 left) decayed into what was essentially a 50-50 proposition, then to sudden disaster.