Wade Miley was such a surprise last year for the Arizona Diamondbacks that the surprise factor might have cost him the Rookie of the Year Award nod in a very close race with Harper. Nobody expected that Wade Miley would be the tenth most valuable pitcher in baseball in 2012. And his 1.79 walks per nine innings and 3.13 FIP were so fabulous that it had everyone scratching their heads. Thus, it is no surprise that Miley is everyone's favorite regression candidate heading into the 2013 season--so much so that it almost makes you root that he proves everyone wrong.
The problem stems in part because Wade Miley was never a prospect despite being a first round pick in 2008. He never made anyone's list of top tier young guys to watch. Plus, he never had the kind of success in the minors that he had in the majors. He never came close to the depth of his walk rate in the minors. For his minor league career, he averaged 3.1 walks per nine innings. How can that turn into 1.79? His minor league ERA was 3.79. So how did he manage 3.33 in the majors? And it was in Arizona no less, where the thin air flies baseballs. Add to all this lack of history, his mundane strikeout rate and skeptics abound.
The walk rate was a result of two things. First, he was very successful at throwing first pitch strikes, which he did at a 60% rate. Combine that with enticing hitters to swing at pitches out of the strike zone, which he did at a 33.8% rate, the 12th highest rate in baseball.
His heat maps show that he pounded the strike zone against right-handed batters low and inside with his fastball and his change up and then threw is curve on the outer half and down in the zone or out of it. It was a potent mix of getting ahead in the count and then putting batters away on his counts. Forget about left-handed batters. They couldn't hit him at all. Left-handed batters had a triple slash line against him of: .200/.238/306.
But, yeah. It makes sense to look at his walk rate and state that he cannot repeat it. But the projections also predict that he cannot sustain his home run rate. His home runs per nine innings of 0.67 seem unsustainable along with his tiny 6.9% homer to fly ball rate. But that particular skill is one he did display all during his minor league career. His minor league homer per nine inning rate was 0.5.
And why can't he maintain that rate? He keeps the ball down almost exclusively. His ground ball to fly ball rate is 1.28. That is not an extreme ground ball pitcher, but it is certainly far from being a fly ball pitcher. So there is really no reason to expect his homer rate to regress. Sure, his walk rate is in uncharted territory, but not his homer rate.
At least most of the projections have him being somewhat successful. All the ones listed on his Fangraphs.com player page think he'll win more games than he loses, will finish somewhere in the 3.60 to 3.90 ERA range with a more normalized walk rate and a slightly higher home run rate. But Baseball Prospectus' PECOTA rating really is a lot more pessimistic.
That system has him finishing with a 10-13 record with a 4.53 ERA and only a 0.9 WARP. That is a pretty heady fall from his 2012 stats.
Again, there is nothing about any of those projections that are arguable except maybe the jump in homer rate. But the possibility is also there that Miley really found something in 2012 and that with more experience, his strikeout rate will improve above middling and he can keep his walk rate down. The key is his first pitch strike rate and getting ahead of the count. If he can continue that trend for another season, the projections will look a lot different next season.