During the postseason, I have been making series win probability charts. They’re available on the front page of the site and regularly on Twitter. I’ve also been calculating championship win probability (cWPA) added for all players. This is similar to single-game win probability added, but in the context of a postseason series. cWPA takes into account the level of postseason series. Each series is twice as important as the previous level. For example, the average play in the League Championship Series is twice as important as the average play in the Division Series. On the extreme ends, the World Series is eight times as important as the Wild Card game.
What follows are the top eleven plays during the 2015 postseason, according to championship win probability added. Note: .077 cWPA can be interpreted as increasing a team’s probability of winning the World Series by 7.7 percentage points.
1) Jose Bautista homers off Sam Dyson (.077 cWPA)
Game Five ALDS
Toronto’s ALDS win probability went from 64% to 94% on this swing. Whether you agree with the bat flip or not, you can’t deny the impact of the play. According to championship win probability added, it was the second biggest homerun by a Blue Jay in postseason history. Of course, the biggest was Joe Carter’s walk-off in Game Six of the 1993 World Series, which was worth .300 cWPA.
2) Jose Bautista homers off of Ryan Madson (.063 cWPA)
Game Six ALCS
Bautista lacks no flare for the dramatic. This homerun increased the Blue Jays series win probability by 13 percentage points (5% to 18%). While his homerun off Dyson a week earlier was a 30 point increase in series win probability, this one came in the ALCS, a round twice as important as the ALDS, making the two very comparable in value.
3) Luis Valbuena homers off of Johnny Cueto (.058 cWPA)
Game Five ALDS
The two runs from Valbuena’s shot were the first on the board in the deciding Game Five and they increased Houston’s series win probability from 42%-65%. Unfortunately for Valbuena and the Astros, they were unable to hold the lead.
4) Daniel Murphy homers off of Zack Greinke (.051 cWPA)
Game Five NLDS
This wasn’t the most memorable play of the series. That goes to the Chase Utley slide. It’s probably not even the most memorable of the game. That would be Murphy’s stolen base after the Lucas Duda walk. However, it did have the most impact. It increased New York’s series win probability from 41% to 62%, giving the Mets a lead they wouldn’t relinquish.
5) Edwin Encarnacion homers off of Cole Hamels (.051 cWPA)
Game Five ALDS
Encarnacion’s tied the game, albeit briefly, and increased Toronto’s series win probability from 39% to 60%.
6) Wade Davis strikes out Ben Revere (.048 cWPA)
Game Six ALCS
The biggest non-homerun of the postseason. Revere struck out in just 10% of his plate appearances during the regular season, but Davis was able to get him swinging with runners at 2nd and 3rd with one out in the 9th. However, there was an obviously questionable strike two call that should have been ball three. The strikeout increased the Royals series win probability from 83% to 92%.
7) Carlos Correa error, scoring two runs (.047 cWPA)
Game Four ALDS
This is an even bigger play when you consider the alternative, a double play that scores just one run. Instead, this play increased the Royals series win probability from 22% to 41%. Correa had been having a tremendous game, with two homeruns earlier. It should be noted that the ball did skip off of Tony Sipp’s glove, making for a very unusual hop for Correa.
8) Rougned Odor scores on Russell Martin’s error (.047 cWPA)
Game Five ALDS
The most bizarre play of the 2015 postseason, very unlikely to be topped. Choo’s bat, Martin’s misfortune and Odor’s heads-up base running increased the Rangers series win probability from 43% to 61%.
9) Eric Hosmer drives in Lorenzo Cain from first base (.045 cWPA)
Game Six ALCS
Multiple people deserve credit for this play. Hosmer for the single, Cain for the amazing hustle, Bautista for not hitting the cutoff man, and third base coach Mike Jirschele for the awareness to send Cain after Bautista threw to Tulowitzki. All-in-all, the play increased the Royals series win probability from 87% to 96%.
10) Daniel Murphy’s RBI double off of Zack Greinke (.042 cWPA)
Game Five NLDS
New York got an early run in the first inning on Murphy’s double. Kiké Hernandez had trouble picking up the ball off the wall, enabling Murphy to take third base. Murphy should be given credit for his hustle and not just coasting into second base. This play increased the Mets series win probability from 44% to 61%.
11) Javier Baez homers off of John Lackey (.042 cWPA)
Game Four NLDS
Baez, who was starting in place of the injured Addison Russell, gave the Cubs a lead on the first pitch from John Lackey. Baez was batting ninth, behind the pitcher Jason Hammel, who extended the inning on a single to center field. The homerun increased the Cubs series win probability from 70% to 84%.
It should be noted there are sure to be bigger plays in the World Series, given the bigger importance in the postseason’s highest level. In the 2014 postseason, the top 18 plays (according to cWPA) came in the World Series.