This week, we turn our attention to stats that measure the odds that a team will win a given game.
Win Probability and its player-driven cousin Win Probability Added (WPA) are stats advanced by Brian Burke of Advanced NFL Stats. Win Probability calculates the likelihood that a team will win the game before each and every play. WPA adds up the impact that an individual player has on those odds.
For instance, a team with a 40-point lead with 45 seconds to play has a Win Probability of 100 percent. Win Probability is a stat that explains what happened after the fact. Swings in Win Probability illustrate which plays had the most impact on a game.
These plays can be charted to produce a graphical representation of the swings of NFL games. For games with twists and turns, these charts can be dynamic.
Case in point, the Jaguars' 14-10 loss to the Browns in week 11 last year. Jacksonville scored the first touchdown of the game, then stopped the Browns in the second quarter. With 9:27 to go in the first half, they had the ball and a seven-point lead. Their odds of winning the game were about 75%.
The Browns soon answered back and tied it up, and the game remained a toss-up until the middle of the third quarter. By the time the Browns scored the go ahead touchdown, they were better than an 80 percent favorite to win with 12 minutes left.
Jacksonville answered with a field goal, but it only took them from a 17% chance of winning to a 38% chance. As the Browns drove for the put-away score with less than five minutes to play, two things happened to save the Jags. First, Alualu and Allen split a sack of Colt McCoy. That was worth about five percent. Then the Browns missed a field goal that would have put them up seven. That was worth about eight percent win probability.
The highs and lows that followed were dizzying. The Jaguars moved the ball into Browns territory, but faced a fourth and one with just 1:26 to play. At that moment, they had just a three percent chance to win. The Browns responded by jumping offsides and, from that moment on, hopes and win percentage were on the climb together.
Aided by another Browns penalty, the Jaguars moved the ball down inside the two-yard line with just eight seconds on the clock. The odds of scoring from the two in two plays were roughly 80%. In just over a minute of game time, the Jags had gone from a three in 100 chance of winning to a four in five chance. Unfortunately, the miracle comeback fell short, as Blaine Gabbert threw two incomplete passes to end the game.
In terms of WPA, Gabbert's final score suffered from the two incomplete passes at the end. He had a decent day but bore a drop of 0.8 points for taking the Jags' win probability from 80 to zero percent with just two throws at the end. Before those throws, his score for the day was 0.11 and, had he thrown the winning touchdown, he would have posted a 0.31 WPA.
WPA isn't necessarily predictive, but it is a fun way to look at how big of an impact each play has on the final outcome.