Alfredo Aceves’ Really Bad Night

Source: FanGraphs

Baseball statistics can be very quirky, especially the ones we carry here at FanGraphs. Players can be worth half-a-win, a hit can produce fractions of the run, stuff like that can be difficult to accept at first. Things happen in wholes in the real world — a team gets credited either with one full win or no win in any single game, that hit either drives in a run or it doesn’t — and understanding that these bits and pieces contribute to the whole isn’t exactly something that gets explains clearly or often enough.

Last night, Red Sox closer Alfredo Aceves lost more than one game. The Sox and Angels played a wild back-and-forth affair with seven total lead changes, including five after the seventh inning. The 29-year-old Aceves was on the mound for three of those lead changes despite only being credited with one full inning of work. He allowed three runs in the top of the ninth to blow a two-run lead, was let off the hook when Cody Ross hit a solo homer to knot things up in the bottom half, then went back out to the mound in a tie game in the tenth only to surrender two more runs.

By WPA, Aceves’ performance was worth -1.021 wins. He pitched so poorly that he cost his team one full win and one-fiftieth of another. His teammates wouldn’t have had to just beat the Angels to get credited with that one full win in the standings, they would have had to beat their own closer as well. There have been approximately 552,000 individual relief appearances made since 1918, and only 23 of them were worse than what Aceves did last night according to WPA. Twenty-three. Baseball-Reference, which uses slightly different WPA calculation than we do, says it was the 14th worst relief appearance in all of baseball since 1918.

A lot of factors go into a pitching appearance that awful, more than the work of one man. Boston starter Franklin Morales didn’t make it out of the third inning, so manager Bobby Valentine had to run through five different relievers before going to his closer. Had the bullpen not been worked so hard earlier in the game, chances are Aceves never goes back out for the tenth. Ross didn’t just hit the game-tying homer in the bottom of the ninth, he also made an error in the top half that led to the run that allowed the Angels to tie. Craig Breslow relieved Aceves in the tenth and allowed the runner he inherited to score what was eventually the game-winning run. Aceves needed some help to perform that poorly and his teammates obliged.

The Red Sox have had one of the best bullpens in baseball this season, pitching to a 3.37 ERA and a 3.83 FIP as a unit. Among 147 qualified relievers though, Aceves ranks 130th in ERA (4.60) and 118th in FIP (4.23). He’s blown seven of 32 save chances, and after last night’s fiasco he’s now 140th out of those 147 qualified relievers in WPA (-1.23). Aceves’ performance against the Angels on Thursday was one of the very worst relief appearances in modern bullpen usage history, costing his team multiple wins in the span of 37 high-leverage pitches.