How Has Mike Fiers Been So Good?

In every start Mike Fiers has made since his debut (seven innings of one-run ball against the Dodgers on May 29), people have been waiting for the bubble to burst on him. After spending the first six weeks of the season pitching not especially well in AAA, the 27-year old right-hander (colloquially known as #TEHFIERS) joined the big-league rotation after a series of injuries and has went on to baffle observers with his success. Despite a fastball that has averaged 89 mph this year, Fiers had posted a 1.87 ERA in the 72 innings leading up to last night’s start against the Reds.

Fiers’ numbers this year have been excellent, but the prospects of a good outing last night still looked grim. Even if their offense this year has been surprisingly average, Cincinnati is arguably the best team in the NL this year, and it would be the first time Fiers would face a club for the second time. If there was ever a game that looked like the one where Fiers was going to come crashing back to earth, this was it.

What happened next was even more mystifying. In a start that was just plain fun to watch, the 22nd-round draft pick scattered one run over eight innings, allowing three hits, no walks or homers, and striking out seven, lowering his ERA to 1.80 in 80 innings. Through six innings, he had a perfect game. Finally, more people than just Brewers fans (at least what’s left of them) took note of Fiers’ dominance, to the point where he is now being mentioned as a Rookie of the Year candidate – and deservedly so. However, this has also raised a few big questions, namely “How has he been so good?” and “Is he going to be able to keep this up?”

Fiers’ minor-league numbers have always been solid, but his performance was always viewed with skepticism, for good reason. Coming up through the minors, Fiers – who was drafted at the age of 24 – was consistently 2-3 years older than the hitters he was facing, and his stuff was never especially good: Fiers’ changeup and control consistently rated among the system’s best, but his upper-80s fastball, slider, and curveball never rated better than average. No prospect list ever ranked him higher than ninth in the Brewers’ system, and his ultimate upside was widely considered to be that of a fifth starter or middle reliever.

Needless to say, he has greatly outpitched that projection so far. However, it doesn’t appear to be a mere statistical fluke. Fiers’ FIP currently stands at 2.20, not far off from his actual ERA, and his .284 BABIP is only around ten points off the league average, and that difference can almost wholly be explained away by Fiers’ propensity for fly balls (his GB% stands at a ridiculously low 31%).

There is no one overwhelming explanation for Fiers’ success, but we can see a few things going on. For one, despite the relatively normal BABIP, Fiers has been very lucky when it comes to the homerun ball. Extreme fly-ballers like Fiers simply can’t sustain rates of .3 HR/9 over extended periods of time. That’s going to return to earth eventually, and, even if Fiers continues to pitch as well as he has been, his ERA will likely regress toward his 3.37 xFIP (which assumes a league average rate of homeruns per fly ball) with time – still outstanding, but not as crazy stupid good as his current mark.

Even after correcting for this, however, Fiers is still pitching much, much better than anyone ever expected him to. It’s worth noting that Fiers developed a cut fastball last year, and the previously seldom-used offering has featured prominently in his repertoire this season. The cutter is a great pitch for getting weak contact and is an easy way to flesh out a pitcher’s arsenal, but unless the pitch is an 80-grade, Rivera-esque offering (Fiers’ is not), it’s not going to make a fifth starter pitch like a borderline ace. The majority of Fiers’ unexpected success simply can’t be explained away, and nobody, from bloggers to broadcasters to prospect experts, seems to know what to make of him or what to expect in a year. However, everyone seems to agree that the pitcher we’re seeing now isn’t the same guy that everyone thought he would be. The Brewers have something here, but nobody is sure exactly what. Stay tuned.