Despite having only 127 plate appearances entering play Monday, David Bote ranks second on the Cubs with a 2.09 win probability added, according to Fangraphs.com. He trails Javy Baez by .41.
And 1.79 of that has come on three game-changing home runs: Bote’s walk-off in the 10th inning to beat the Reds 3-2 on Friday, his walk-off grand slam in the ninth to beat the Nationals 4-3 on Aug. 12 and his two-run homer in the ninth that tied the Diamondbacks on July 6 before Anthony Rizzo followed with a walk-off homer for a 7-6 victory.
WPA measures how much each plate appearance adds to or subtracts from a team’s chance of winning. By WPA, Baez and Bote are followed by Anthony Rizzo (1.88), Ben Zobrist (1.59) and Jason Heyward (0.91) on the Cubs’ list.
Bote has had an unusual number of high-leverage opportunities. WPA/LI (win probability added divided by leverage index) adjusts for that. Leverage index is a measure of the average importance of a player’s plate appearances in a game situation.
So WPA/LI tells us how much a player has added to his team’s win expectancy relative to opportunity. By that measure, Baez remains the Cubs’ leader at 2.36, followed by Rizzo (2.25), Kris Bryant (1.12), Zobrist (1.08), Bote (1.07) and Kyle Schwarber (1.05).
When Bote stepped to the plate with one out and no one on Friday, the Cubs had a 58.3 percent chance of winning. Historically, home teams in that position have won 58.3 percent of the time.
Bote’s homer took the Cubs’ chances to win to 100 percent and added .417 to Bote’s WPA — the difference between a 1.000 shot to win and .583.
The grand slam against the Nationals rocketed the Cubs’ chance to win from 9.9 percent to 100 percent, and Bote added .901 in WPA. And the two-run homer against the Diamondbacks increased the Cubs’ shot to win from 11.1 percent to 58.3 percent, good for .472 in WPA.
The blast against the Diamondbacks left the Cubs in a tie game at home with one out and nobody on. Rizzo came up with the same 58.3 percent chance of a Cubs victory that Bote did against the Reds, and he also added .417 to his WPA with his walk-off.
Two of Bote’s other three homers were good for a tie or the lead, but they came in earlier innings with less leverage. He added .111 in WPA when his homer in the second inning tied the Tigers 1-1 on July 4 and .215 when his two-run homer in the fifth gave the Cubs a 2-1 lead against the Tigers on Wednesday.
Not all homers are created equal. Schwarber’s two-run shot in the seventh during a 9-0 romp Sunday against the Reds came with the Cubs leading 7-0 and having a 99.6 percent win expectancy. Schwarber increased that to 99.9 percent and put .030 on his WPA.
WPA can go down as well as up. Baez’s 2.50 WPA consists of 11.73 in plate appearances with positive outcomes and -9.23 at other times. It’s +4.20 and -2.11 for Bote and +10.77 and -8.88 for Rizzo.
WPA and WPA/LI are not good predictors of things to come. There is no tendency for high WPAs to stay high or for low WPAs to stay low in following seasons.
For this season, however, it gives us a way to quantify how big a difference Bote and his game-changing homers have made.