Wide Range of Outcomes Possible for Wade Miley

After his 194.7-inning, 2.9-WARP season in 2012, Wade Miley’s results have mostly been trending downhill. The 3.33 ERA slipped to 3.55 in 2013. In 2014, his ERA slipped to 4.34. Even advanced stats have been all over the place so far in Miley’s career, but one thing has remained constant: high innings totals with a left arm all the more rubbery because of its high gluten content. Miley is as good a bet as any to contribute 30+ starts.

After that, though, Miley in a Red Sox uniform is hard to get a read on. PECOTA likes his chances of a breakout (28%) and feels fairly confident in improvement (58%), but even PECOTA agrees that there’s a wide range of outcomes; there’s a difference of two wins between his 30th percentile projection (-0.9 WARP) and 70th (1.1 WARP). For Clay Buchholz and dozens of other recently inconsistent pitchers, the comparable gap in WARP seems to max out around 1.5 wins. If Miley is going to be a fascinating watch, it’s largely because of this particularly wide array of possible outcomes – and because of why that may be the case.

2013 Miley was the same man as 2012 Miley with respect to ERA and K/9, but not BB/9 and GB% and (therefore) FIP. 2014 Miley was the same man as the 2013 version with respect to BB/9 and GB% and FIP, but not ERA, and definitely not to K/9, where he certainly looked like a different man. The exact jump in K/9 is a little misleading because Miley was facing more batters per inning, but even expressed as K%, the jump from 17.4% (62nd of 81 qualified) to 21.1% (29th of 88) is substantial. The main takeaway from his body of work with Arizona is that if he took a step down, it was probably before 2013 and not after it.

The strikeouts-aplenty version of Miley could stick around. Showing improved fastball command, he seemed to differ his approach in his very first game of the season, which made him the record holder for MLB strikeouts in the Southern Hemisphere. His change of team, league and receivers nonetheless point in different directions.

He Could Be Worse

Pitching in the American League could have a real impact on Miley. Even in a somewhat lackluster 2014 season, Miley held “batters” in the ninth spot to a .115/.125/.128 line; in all other spots, .262/.327/.411. That doesn’t make him unique among players transitioning from the NL to the AL, of course, but the fact that he’s a southpaw could make a difference. Miley has experienced much success against lefties in his career, as you would expect. His platoon split has evened out somewhat over time (see below), but even last year, he was doing more or less what he wanted against lefties, with an 8.1% fly ball rate and 64.7% ground ball rate.

It’s not just that DHs are probably better hitters than pitchers — it’s that for Miley, the DH position will offer a particularly high percentage of batters hitting from the right side. In 2014, plate appearances from the DH position in the AL shifted so that left-handed batters appeared just 18.7% of the time. And it gets worse. With more and more teams relying on platoons and other timeshares and using the DH position as a roster safety valve, the lineup card tends to get filled out with the platoon advantage in mind. Against lefty pitchers, the percentage of PA by lefties at the DH position plummets.

According to the Baseball-Reference Play Index, lefty hitters playing DH in the AL combined for a total of just 364 PA against southpaws last season. More than half of those were tallied by David Ortiz (195), and most of the rest were logged by Adam Dunn (71) and Raul Ibanez (46). Miley won’t face any of those three hitters in 2015, at least in a Red Sox uniform — and per the BP depth charts, no lefty is slated to get anywhere near as much playing time at DH as Ortiz. It’s not quite as simple as replacing pitcher PA with these DH ones — chances are that for many teams who ended up with a right-handed batter as a primary DH, they made an extra effort to fit in an extra lefty elsewhere (perhaps one harder to replace). When it comes to the DH spot in the order, however, Miley may be facing a right-handed hitter around 98% of the time.

Another issue? Wade Miley was a member of one of the top pitch-framing batteries in baseball last year, at least among those with over 1,000 framing chances as defined at Baseball Prospectus. Maybe he and Miguel Montero got a little lucky with the umpires they worked with, etc., but it’s also at least possible that Montero’s particular framing skills happened to match Miley’s pitches and pitching style. Ryan Hanigan may be a soft pillow for Miley to land on, but any time a pitcher gets taken away from demonstrated success with a Montero-quality framer, we have to at least raise an eyebrow.

He Could Be Better

There are also reasons for the Red Sox to think that saving Miley from the D-backs will benefit him (maybe that’s why he returned the favor). The first is pretty simple: Chase Field. Pitching in Fenway is no picnic, but Chase Field enjoys offense-promoting elevation, heat, dry air, and dry baseballs. The dry baseballs have the biggest effect; Alan Nathan has estimated that a humidor at Chase could reduce home runs by 45±9%, later updating that figure to 37% or so. The stadium’s large dimensions go a long way toward mitigating that effect, but Miley will get to enjoy a better field in terms of HR Factor, at least in terms of the 2014 BP statistics. It is, at the very least, extremely unlikely that Miley will put up another 1.0 HR/9 ratio, even from a luck perspective.

Just being gone from the team that plays at Chase may also be a factor. Arizona was 28th in Defensive Efficiency last season — and while the Red Sox weren’t particularly great last year (21st) and the likely defense has changed, chances are pretty good that the change in defense will only help him. Miley’s ERA was nearly .4 runs above his FIP, .67 runs above his SIERA. You may recall the minor pitching apocalypse that befell the D-backs at the beginning of 2014, but the entire staff struggled all year, with a .77 run gap between its SIERA and ERA even larger than what Miley experienced individually. The weirdest stat yet: the D-backs staff had the 10th best SIERA.

It may not be a coincidence that two pitchers who had once been above average in Ian Kennedy and Brandon McCarthy struggled mightily in Arizona, both excelling with other teams after successive deadlines. This isn’t confirmation of anything by itself, but McCarthy did have a 2.02 run gap between ERA and SIERA with the D-backs last year — and an ERA .1 runs better than SIERA with the Yankees. When Kennedy was traded at the 2013 deadline, he sported a 1.07 gap — only to see that shrink to 0.18 since. These are cherry-picked examples (they may not have been traded if not being paid as above-average without results to match), but if you’re looking for reasons to be optimistic, they’re there.

What to Watch For in 2015

In 2014, Miley upped his strikeout rate while maintaining his over-50% ground ball rate, and a lot in 2015 may depend on whether he continues to try for both things. Last season, Miley de-emphasized his sinker early in counts; in the preceding two seasons Miley’s first pitch was a sinker over 50% of the time, but that dropped to 41.92% last year. That may have helped him rack up the strikeouts, but we might see the Red Sox coach him to returning to the sinker more — especially on a staff that now also features Rick Porcello and Justin Masterson.

Any difference in approach will be fascinating to watch, but none more so than his habits against lefties, against whom he almost never throws his curve or change. But even the balance of his fourseam/sinker/slider mix has already changed significantly against lefties. In his best 2012 season, he favored the fourseam against lefties and sported a very good 1.86 True Average against them. Since then, his slider has played a bigger and bigger role (from 25% usage to 36%, per Brooks Baseball), and his platoon split has evened out quite a bit.

It seems that Miley picked up more strikeouts in part through his increased reliance on late-PA sliders, but the the increased reliance itself may have come with a cost. Against lefties, Miley’s extra sliders were largely in slider counts — especially when he was ahead (up to 43% from 32%; up to 49% from 37% in the overlapping set of pitches with two strikes). Righties slugged just .284 against Miley’s slider in 2014, but lefties did most of their damage against it, with a .432 slugging mark. Lefties had slugged just .263 against the slider the year before. The numbers aren’t very large, but if Miley’s opponents did start to look for the slider once they were down, it would help to explain why more of his longer at-bats turned into hits.

Miley’s pitch tendencies can change just as easily as his uniform and the defense behind him did. We may find that PECOTA was right on and that Miley is barely better than replacement level. It’s also possible that Miley will crash and burn, or that he will excel as kind of a poor man’s Jon Lester. With so many meaningful things going both ways, watching what happens next with Miley in 2015 should tell us a lot about what to expect in the long run.