Which White Sox pitcher has made the most of his chances to cement the opportunity to win?
That would be Lance Lynn, who leads the staff with a win probability added (WPA) of 2.86. The Sox have won about 2.86 more games than they would have with average results instead of Lynn results in his appearances.
But not all pitchers get equal opportunity to add WPA. Adjusted for the average leverage a pitcher faces, the Sox’ leader is Carlos Rodon at 2.65.
Every plate appearance has equal and opposite effects on batter and pitcher WPAs. When Liam Hendriks struck out the Indians’ Amed Rosario to close the Sox’ 5-2 victory Sunday, the Indians’ chance of winning dropped from 1.6% to zero.
Accordingly, 0.016 was added to Hendriks’ WPA for the season, and 0.016 was subtracted from Rosario’s WPA for 2021.
WPA is mentioned more often for hitters than for pitchers. But, as you would expect with a staff that has allowed the fewest runs in the American League, Sox pitchers have added much to the team’s probability of winning.
Lynn’s 2.86 WPA is followed by Rodon’s 2.17, Lucas Giolito’s 1.63 and Hendriks’ 1.53.
Other WPAs among Sox pitchers include Garrett Crochet at 1.01, Michael Kopech at 0.56 and Dylan Cease at 0.40. Dallas Keuchel trails the staff at -1.29.
WPA rises or falls with every plate appearance. Not all plate appearances are equal. A leadoff walk in the ninth inning of a tie game has a greater impact on WPA than a walk in a blowout or in the early innings.
A starter who pitches in more close games has a greater chance to add or subtract WPA than one who pitches in a lot of blowouts. Closers often face high-leverage situations and can post high WPAs despite few innings. If they fare poorly, their WPA can go negative in a hurry, as in the case of Craig Kimbrel’s -0.52 in 22 innings since joining the Sox.
To adjust for differences in opportunities, WPA can be divided by a leverage index (LI) that represents average leverage against a pitcher. When putting pitchers on even ground with WPA/LI, Rodon is the Sox’ leader at 2.65, followed by Lynn at 2.54, Hendriks at 1.36 and Giolito at 1.28.
WPA also is used in a stat Fangraphs.com labels ‘‘Clutch.’’ It subtracts a pitcher’s WPA in average situations from his WPA in high-leverage situations.
Codi Heuer led the Sox at 0.96 Clutch before he was dealt to the Cubs. Among those still on the South Side, the leaders are Giolito (0.52), Lynn (0.31) and Keuchel (0.30). Hendriks (-0.32) and Rodon (-0.53) are in negative numbers.
No doubt you’ve spotted a problem. Pitchers are compared to themselves, so a positive Clutch means Keuchel struggled a little less when the leverage was high. Rodon, who is very good in high-leverage situations, comes up as negative Clutch when compared to his performance in average situations, which has been outstanding.
Clutch or not, you still rather would have Rodon on the mound.