Stats detailing WE, WPA lend perspective to playoff games
Win expectancy and win probability added are intertwining ideas evaluating a team’s chance to win and each player’s contribution. The Cubs have seen wild swings in both during the postseason.
Want to know a team’s chance of winning given the situation at any point in the game? That’s win expectancy, or WE. Want to know how much a plate appearance has raised or lowered the win expectancy? That’s win probability added, or WPA.
When the Dodgers’ Adrian Gonzalez stepped to the plate Sunday to lead off the second in Game 2 of the NLCS, the Cubs’ WE was 50 percent. It was a tie game, and both teams had the same number of outs remaining. After he homered for the only run, the Cubs’ WE sank to 39 percent.
That 11 percent difference can be translated to WPA for Gonzalez. For that plate appearance, his WPA was .110.
Players’ WPAs are cumulative for the season. In the regular season, the Cubs’ Anthony Rizzo was third in the National League with a 4.32 WPA, behind the Diamondbacks’ Paul Goldschmidt (4.52) and Reds’ Joey Votto (4.39). That has not held up in the postseason, with Rizzo at -.27 and Cubs leader Javy Baez at .72.
The Cubs played games with WPA heroics and large WE swings in Game 1 vs. the Dodgers and in the clinching NLDS Game 4 vs. the Dodgers. In an 8-4 victory over the Dodgers on Saturday, the Cubs’ WE stood at 87.3 percent when they entered the eighth with a 3-1 lead, plummeted to 48.6 percent when Gonzalez’s bases-loaded single drove in the tying runs and he stole second, then shot up to 98.7 percent on Miguel Montero’s grand slam in the bottom of the inning.
One game before, the Cubs entered the ninth against the Giants trailing 5-2 and with a WE of only 2.5 percent. Here’s how that changed in a hurry:
† Kris Bryant singled. WE, 5.8 percent; Bryant WPA, .033.
† Rizzo walked. WE, 13.1 percent, Rizzo WPA, .073.
† Ben Zobrist doubled, driving in Bryant. WE, 34.5 percent. Zobrist WPA, .214.
† Willson Contreras singled, driving in Rizzo and Zobrist to tie the game. WE, 58.2 percent, Contreras WPA .237.
† Jason Heyward bunted into a fielder’s choice, Contreras out at second, Heyward taking second on an error. WE, 56.5 percent; Heyward WPA, -.017.
† Baez singled home Heyward for a 6-5 Cubs lead. WE, 86.4 percent. Baez WPA, .299.
Just like that, the Cubs zoomed from a 2.5 percent chance of winning to 86.4 percent. Each hit or walk meant more to the WPA as the Cubs neared tying and winning situations. Rizzo’s walk brought the tying run to the plate, so it had a higher WPA than Bryant’s single.
But WE can never reach 100 percent until the last out is recorded or the winning run scores in a walk-off situation. It can get close — Dexter Fowler’s home run after Montero’s slam took the Cubs to 99.5 percent, but that perfect 100 has to wait.
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