JABO: Bad Bullpens Through History

After another loss on Tuesday night, the A’s stand 14-27, the worst mark of any team in baseball. That record comes in spite of the fact that they’re 5th in the majors in runs scored (184), and have “only” allowed 190 runs to their opponents; being outscored by six runs over 41 games generally does not lead to a disastrous win-loss record, but that’s where the A’s find themselves after the first quarter of the season. And as is often the case when a team’s record doesn’t match their run differential, the blame can be laid almost entirely at the feet of the A’s relievers.

At the most basic level, you could just look at their 4.99 bullpen ERA — 29th in the majors — and conclude that they’ve struggled, but ERA is not a great tool to evaluate pitcher performances, and it’s especially poor at evaluating relief pitcher performance, because often their job is to come in and squash a rally; if they fail, the starting pitcher’s ERA is the one that goes up, so ERA won’t reflect bullpen performances in those situations.

And, of course, not all runs are created equal, especially late in the game. If you’re up 10-3 in the eighth inning and your bullpen gives up a few runs, it’s not a particularly big deal, as you’re extremely likely to win the game anyway. So when discussing a bullpen’s impact on a team’s record, we care not just about the number of runs they allow — whether ERA blames them for it or not — but also the distribution of when they allow those runs, and whether more of them happen to be coming in situations where giving up even a single run can have a dramatic outcome on the game.

Evan Scribner is a fantastic example of how different a reliever’s performance can be from their traditional numbers. If you just look at his overall line, it appears that he’s having an excellent season; 23 innings, 17 hits, 2 walks, 27 strikeouts, and a 2.38 ERA. Even newer-fangled pitching numbers like FIP (2.30) and xFIP (2.20), that are designed to better isolate a pitcher’s performance, think very highly of Scribner. From a context-free standpoint, Scribner has been terrific, but once you look at the distribution of his performances, you find a somewhat different story.

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