The Diamondbacks rotation scuffled in 2016, with Archie Bradley, Patrick Corbin, and Shelby Miller being the faces of that struggle. The Diamondbacks are banking on them rebounding in 2017 with better catching behind the plate with Welington Castillo likely to be elsewhere and Jeff Mathis catching a few of their starts this year. The team is best served to find another quality handler of the pitching staff to split up the duties behind the plate furthermore.
Shelby Miller: While Miller’s fastball velocity was down in 2016, it was trending in the right direction at the tail-end of the season. Miller was at his best in 2015 when he was mixing in his three fastballs, with the sinker and cutter down in the zone and the 4-seamer up in the zone. Miller is a North-South pitcher that changes eye levels with his different fastballs and uses the curveball and change-up right off of it to keep hitters off-balance. Miller’s peripherals, batted ball profile, and plate discipline numbers were near identical to his 2014 marks, except for a difference of 84 points of BABIP (.256 in 2014, .340 in 2016). Miller’s first pitch strike rate wasn’t too far off his career marks, posting 59.4% relative to a career 60.8%, so you really can’t blame that too much. A lot has to do with poor defense, poor luck, and poor sequencing with an RE24 of -26.22, opposing hitters batting .337/.419/.704 (193 sOPS+) with RISP with a 20/15 K/BB ratio.
With a new regime in place, Miller has a clean slate to work with. The raw stuff is still there with Miller hitting 93-96 MPH with the 4-seamer late in the season. What he needs to work on is getting left-handed hitters out. Lefties put up a 153 sOPS+ (.329/.401/.542 slash), although righties fared well with a 117 sOPS+. One potential solution would be using the cutter and work it inside on their hands to produce weak contact. Against righties, the primary out pitch should be the combination of 4-seam and 2-seam, with the 4-seamer up in the zone and the 2-seamer down, and curveballs to change speeds. I think the signing of Jeff Mathis helps Miller the most of all the struggling pitchers due to his glove work, especially down in the zone. With no favorable platoon splits that could suggest a bullpen role, Miller is going to either make it as a starter or not at all.
Patrick Corbin: Corbin’s stuff flattened out in 2016 and he got hit hard for it. Some of that can be attributed to the Tommy John surgery he had in 2014 and another due to the rust of not being used to preparing for a full season in 2 years. As a starter, Corbin really struggled as batters hit .302/.371/.497 (131 sOPS+) and batters posted a hard hit rate of 40%. That pre-empted the team to move him to the bullpen for the final 6 weeks of the season, where his stuff looked more sharp and the increase in fastball velocity from 91-93 to 93-96 really made a difference. The question becomes long term viability, starter or reliever?
Corbin’s projected salary stands at $4.2M, so I would expect the team to try to see if he can rebound as a starter before casting him off to the bullpen. That salary is too expensive for a non-closer on a non-competitive ball club with a small market payroll. Corbin is at his best when he’s able to bully right handed batters inside with his fastball and put them away with a back-foot slider. Corbin is really a two-pitch guy with a solid fastball and excellent slider. Last year the team forced him to throw his change-up more and it produced bad results. Of the three pitchers, Corbin has the most MLB utility because he can always move to the bullpen and turn into a relief ace like Andrew Miller. If Corbin is able to rebound as a starter, I see him most likely getting moved at the trade deadline because he can help a contending team as either a #3/4 starter in a playoff rotation, a multi-inning reliever, or both.
Archie Bradley: Bradley is a former Top 10 pick who hasn’t been able to put things together the last three years. Bradley started 2016 with a dominant run in Reno that put him back in the major league rotation for good in late May. Results were mixed, but we saw flashes of potential, but Bradley was still as inconsistent as before. His strikeout rate improved and he cut his walk rate a bit, but struggled with a high BABIP and low strand rate. If you go by Fangraphs, his peripherals have him as a league average pitcher, but his poor results on balls in play reduced his RA9 WAR to 0.7. Bradley has earned a shot to compete for the rotation and his high strikeout rate makes him a possible bullpen candidate, especially with strong splits against right handed batters (81 sOPS+).
For Bradley, the issue is finding a usable third pitch. He has a pretty solid fastball that sits 92-94, and can hump it up to 95-97. His curveball when on is a plus-plus pitch, but as a feel pitch can be hit or miss. Bradley had worked on using a cutter in the 2014 fall league, but the last regime made him scrap that pitch and essentially made him a two pitch guy. I think the new regime should allow him to re-introduce that pitch and if he needs help working with that pitch, he should consult his pitching strategist on how to improve that pitch (and also his Twitter game). In addition, Bradley needs to figure out how to get left-handed hitters out or he’ll wind up in the bullpen instead of the rotation. I suggest that cutter be an option due to a non-existent change-up.
Conclusion: My projection has Bradley and Miller starting over Corbin due to having more upside, but realistically they are all equal in my book. Corbin has the most MLB utility, Miller has the most upside, and Bradley has the most team control remaining. Even though my projeciton has Bradley over Corbin in the rotation, I could see the Diamondbacks using Corbin and Miller in the rotation to see if they can rediscover his All-Star form. Corbin and Bradley due to positive platoon splits against the same hand would make solid bullpen candidates should either not make the rotation.