The arrival of Zack Greinke and Shelby Miller means that there appear to be four rotation spots locked down, health permitting, for our Opening Day roster. Greinke, Patrick Corbin, Miller and Robbie Ray appear all but certain of their positions, leaving just one slot to be decided. There are certainly no shortage of contenders for it, so let's take a look at some of the possible candidates - who include most of the members of our Opening Day rotation from last year
Over the past two years, nobody has made more starts for the Diamondbacks than Anderson's 48. But as last year, when it was the very end of March before he was publicly anointed a starter, he finds himself again competing for a job in spring. That's because, after an excellent start to the season, with a 2.84 ERA through his first 13 starts, the wheels fell off Anderson and only a injury to colleague Jeremy Hellickson the following day, saved Anderson from a trip to Reno after being optioned there on August 19. He was decent enough thereafter, with a 3.48 ERA in his final six outings, but it seems too early to proclaim Anderson "fixed".
Bradley squeaked into the 2015 Opening Day rotation even later than Anderson, snagging a spot only after Trevor Cahill was traded to the Atlanta Braves on April 2. His potential was clear early, but the brutal line-drive he took to the face on April 28 almost seemed to have knocked his talent loose. Four horrible starts later, he was sent back to the minors, then there were shoulder issues that limited him to 29.1 minor-league innings after June 1 and an extended stint in instructional league ball. Bradley has changed his delivery, and believes it's now more repeatable. We'll see the effect of that in the coming weeks.
Rubby De La Rosa
The third and final of those Opening Day rotation members is the hardest working man for Arizona last season, and it wasn't close with De La Rosa throwing 36 more innings than anyone else. That may not be of significance in 2016, but given they weren't particularly good innings - an ERA+ of only 87 - does suggest the team is willing to tolerate bumps in the road as Rubby hones his craft. Achieving greater consistency with his performance, and figuring a way to get left-handers out (they burned him for a .949 OPS last season), will be key for Rubby, who will also turn 27 during spring training, and really needs to start delivering on his stuff.
Coming out of nowhere in 2015 was Godley, He was pitching for High-A Visalia as late as June 19, and less than five weeks later, Zack made his major-league debut - and didn't disgrace himself, going 5-1 with a 3.19 ERA over six starts and three relief appearances. I think there's a suspicion this could be over-achievement, given Godley's unheralded advance (he was #38 on John's prospect list at the end of last season), and a 4.33 FIP does suggest he'll need to walk fewer people to have long-term success going forward/. But given how many shifts in level and role he had this season, I think he certainly performed better than expected.
While Huddy has made no secret of his desire to return to the rotation (not least as free-agency beckons at the end of this season), it's going to be a difficult road back to becoming a full-time starter. Save a 3.1 inning emergency outing in May, his last major-league start was June 2012, and he hasn't reached even 70 IP since 2011. Any such effort here would likely involve either a minor-league stint and/or an abbreviated season, in terms both of pitches per outing, and overall innings worked: after not one but two Tommy John surgeries, you do not want to push anything. But will a part-time starter fit in with the D-backs' apparent "win now" mentality?