The 10 Best Strikeout Relievers in Major League Baseball

Sean Doolittle, Oakland Athletics

The A's need Sean Doolittle back. Happily for Oakland, he's expected to return this weekend, as the team who had been the best in baseball for most of this season is now barely hanging onto a playoff spot by the skin of their teeth.

The A's bullpen has had trouble locking down games in his absence, especially in the last week. It's tough to be without the closer who has struck out 38.7% of the hitters he's faced this year, tied for sixth-best among all MLB relievers. His nERD of 1.06 and rWAR of 1.4 are both among the best in the league, and his 2.28 ERA belies his FIP of 1.44, although both are very good.

The 27-year-old left-hander has a terrific fastball for a left-hander, averaging 94.5 miles per hour, which he throws most of the time (94.1% of all his pitches). He mixes in a slider and changeup to keep hitters off balance, and has kept both lefties and righties down, holding right-handed hitters to a .193/.223/.308 slash line this season.

Oakland just hopes the rest of their bullpen can hang on long enough for Doolittle to get back to his 9th inning role this weekend.