How much can one outing change a pitcher's entire season? Starting pitchers are relatively insulated by the number of innings they throw, though there are rare cases where a bad outing can significantly impact their total season numbers. Remember Rick Porcello's awful start against the Los Angeles Angels in 2013? That inflated his ERA by nearly half a run.
Relief pitchers' numbers are in even more peril when an outing goes awry. Justin Miller had decent numbers in a short spell in the major leagues heading into August, but allowed three runs on five hits in two innings against the Pittsburgh Pirates. His season-long ERA jumped by over 1.5 runs, and he did not pitch in the majors again this season.
That last outing doesn't tell the whole story, though. Picked up by the Tigers after he was released by the Texas Rangers in 2013, Miller was expected to be one of the arms that contributed out of the bullpen at the big league level in 2014. He started the year in Triple-A Toledo, where he worked four consecutive scoreless outings to open the season. He was called up shortly after, and started his big league career with four more scoreless outings to close out the month of April. To that point, Miller had thrown 10 innings, allowing one run on seven hits with nine strikeouts to one walk. Not bad, right?
Of course, it didn't last. Miller was tagged for five runs (three earned) in his next two outings, raising his MLB ERA up to 4.32. The Tigers kept their faith, and Miller rewarded them by picking up his first big league win with two scoreless innings against the Baltimore Orioles on May 13th. However, Miller was sent down shortly after, the victim of needing more fresh arms for the bullpen as the team headed to Boston.
At this point, Miller's numbers were still pretty solid. He had allowed a combined 2.40 ERA in 15 innings across Triple A and the majors with 11 strikeouts and two walks. It would only be a matter of time until he was called up again, unless things completely unraveled in the minors.
They didn't, but that still did not lead to another call up for the 27 year old right-hander. Miller allowed just six runs in his next 27 outings for the Mud Hens, a 1.65 ERA. He had a 3.0 strikeout-to-walk ratio and 0.89 WHIP during that stretch. Opposing batters hit .175/.248/.237 against him. Despite these gaudy figures, it took nearly three months before Miller made his way back to Detroit. Then, he had that aforementioned outing against the Pirates. His MLB ERA jumped from 3.48 to 5.11. His WHIP leapt from 0.97 to 1.30. Even his FIP jumped by a full run, from 3.71 to 4.92.
Miller was slightly more vulnerable after being sent down a second time, allowing three runs in his final 7 1/3 innings to close out the season.
If only I could grade Miller's entire 2014 season instead of the 12 1/3 innings he had at the MLB level. His overall numbers were excellent -- he had a 2.53 ERA and 3.14 strikeout-to-walk ratio in 57 combined innings this year -- and it's a mystery as to why he wasn't given another chance at the MLB level sooner than August when he was so thoroughly dominating Triple A hitters. Will he be given a bigger role in 2015? Your guess is as good as mine, but it wouldn't hurt to give him another shot at translating his minor league success to the majors.