The Arizona Diamondbacks will have to reconsider their Opening Day rotation after the latest update on Merrill Kelly. Nick Piecoro of The Arizona Republic reports that tests on Kelly’s injured back revealed no structural damage. However, the right-hander told reporters that his Opening Day start is “probably off the table.”
Kelly first experienced discomfort in his mid-back on February 20. He was scratched from a live batting practice session that day. He underwent a series of tests, which included an MRI and a CT scan.
While the Diamondbacks can feel some relief that there isn’t a bigger injury, they may be without one of their best starters to begin the season. Piecoro adds that Kelly still feels the discomfort when he throws in catch-play.
Diamondbacks Rotation Without Merrill Kelly
With Kelly likely sidelined for Opening Day, that changes the rotation a bit. It makes the decision to re-sign Zac Gallen on a one-year deal prescient in hindsight. Bringing him back allows Arizona to maintain a stable rotation while Kelly is out.
Gallen could still line up for Opening Day if the Diamondbacks tweak their schedule. His first Cactus League outing will come on February 25 against the Los Angeles Dodgers. That gives manager Torey Lovullo a 29-day window between this outing and Opening Day.
Assuming no further injuries, the other four rotation spots will be taken by Ryne Nelson, Brandon Pfaadt, Eduardo Rodríguez, and Michael Soroka. Kelly may be a candidate to open the season on the 15-day injured list while the Diamondbacks try to find out more about his injured back.
Rodríguez and Soroka already have concerning injury histories, which suggests they might not have enough depth to get through the season. They’re only one further injury away from having to rely on unproven arms.
Cristian Mena is the only depth starter on the 40-man roster with any major league experience. However, he has only one career start and 9.2 innings to his name. Injuries have cost him a lot of time and opportunities the past two seasons.
But there’s also a case for him to make the Opening Day roster as a long reliever who can eat up innings while stretched out. Kelly’s injury complicates Mena’s path to the big leagues and almost guarantees he stays stretched out as a starter all season.
Diamondbacks Starting Pitching Depth Options Without Merrill Kelly
Beyond Mena, the Diamondbacks have Dylan Ray, Kohl Drake, and Mitch Bratt. Ray has the most experience at Triple-A, with 18 starts and 90 innings at the level. Drake has a handful of starts and Bratt pitched all of 2025 in Double-A.
This spring will likely determine the depth chart for these pitchers. Although the timing of a rotation injury may also impact who gets called up. Mena, Ray, Drake, and Bratt already have their 40-man clocks started and still have minor league options remaining. Mena has one, while the other three pitchers have all three.
Outside of the 40-man roster, the team has Yu-Min Lin and Spencer Giesting as call-up candidates.
However, it was also telling that general manager Mike Hazen gambled on leaving Giesting off the 40-man roster. While that gamble paid off, as the left-hander was not selected in the Rule 5 Draft, it might not be a sign of confidence in him as a rotation option.
The Diamondbacks are treading a very thin line with their rotation to begin with. The Kelly injury gives them an even thinner margin. Arizona will have to hope the rotation holds up until he gets back from this injury.
Diamondbacks’ Rotation Gets Dangerously Thin After Merrill Kelly Update