SCOTTSDALE, Ariz. -- The top two pitchers in the Arizona Diamondbacks' rotation have received a ton of attention. But the third member of this group could be a real difference-maker in providing the kind of rotation depth a contender requires.
Zack Greinke signed with Arizona, setting a record for average annual value in a pitching contract. Shelby Miller came at a high price in prospects in a trade with Atlanta. The D-backs had invested heavily in both cases, but in so doing, they have obviously improved their chances in the National League West.
But as much attention as Greinke and Miller have attracted, there will be three other spots in this rotation. And the No. 3 spot appears to be in particularly good hands with left-hander Patrick Corbin.
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Corbin, 26, was off to a promising start when his career, like so many others, was interrupted by Tommy John surgery. That cost him the 2014 season. Corbin came back to pitch capably over 16 starts in 2015 (6-5, 3.60 ERA).
But for quality pitchers, the second year after Tommy John often brings a return to their better form. From his work in the Cactus League this spring, that appears to be where Corbin is headed.
At this point, looking at Corbin work does not leave anybody with a coming-back-from-Tommy-John frame of reference. Instead, the image is much more distinct; a left-hander in command of his craft. Four-seam fastball, sinker, slider, changeup; they're all available and working for Corbin.

"He's commanding all his pitches," D-backs manager Chip Hale said Monday night. "He pretty much can throw any of his pitches in any count. And those are weapons that not a lot of pitchers have."
Monday night at Salt River Fields in a 3-2 win over a split-squad version of the Milwaukee Brewers, Corbin made his fourth 2016 Cactus League start. He gave up one unearned run over 5 1/3 innings, lowering his ERA this spring to 0.63. Corbin gave up five hits and walked just one, while striking out seven. He threw 74 pitches, 47 for strikes. Corbin's pitch count would have been even more efficient, but three errors by third baseman Jake Lamb forced him into more work.
This is the full-fledged renewal of what had been a very promising career. Corbin feels understandably positive about the way things are developing with his stuff and with his overall health. A developing changeup is part of the package, but so is a pervasive sense of physical well-being.
"Everything feels great, and I felt strong there near the end, as well," Corbin said of his performance Monday night. "The changeups are the biggest things I've worked on. The change is progressing to the point where I feel that I can throw it in almost any count. I honestly think the changeup is helping my fastball where it's maybe getting on guys, and I'm getting more strikeouts on that pitch.
"Still trying to go out there and work on things. Just trying to locate, I think that's something I've been able to do so far."
Corbin joked that his pitch count was similar to what he could have expected for an entire night of work last season. This year, a pitch count in the 70s is just a step toward something bigger and better.
"And the recovery has gone really well for me, as well," Corbin said. "I've been able to go back and feel just as strong every start, and that's something I struggled with last year coming back.
"I feel like normal now. It's great to be back and get that pitch count back up close to 100 by the end of this camp."
Corbin may be the No. 3 starter in this rotation, but with the talent in front of him that's understandable. The point is, based on what he has demonstrated this spring, he could make the middle of this rotation look a lot like the top of some other rotations. Any way you want to measure it, Corbin's return to full health and effectiveness will be an important component in making the D-backs legitimate contenders.