What the return of Merrill Kelly means for Diamondbacks’ rotation

PHOENIX – The return of Merrill Kelly to the Diamondbacks’ starting rotation will leave manager Torey Lovullo and general manager Mike Hazen with very important decisions to make. 

After a successful rehab start in Triple-A Reno, Lovullo believes Kelly is prepared to make his 2026 debut against the Baltimore Orioles on Tuesday. 

“He felt good, looked good, (Kelly) seems to be in a very good spot,” Lovullo said. 

The big decision management will have to make is what to do about the current rotation. 

Will Lovullo use a six-man rotation? If not, who gets replaced, and what happens to that pitcher?

Lovullo said on Arizona Sports 98.7 FM Friday that there are “no plans” to transition to a six-man rotation, so fans can cross that option off the list. 

“You know that we love building depth; starting pitching depth is really important in this industry,” Lovullo said. “I don’t know exactly what we’re going to do; whether it’s sending a guy to Triple-A or putting them in the bullpen has not been decided.” 

Initially, the consensus was that right-hander Michael Soroka was the most likely to move to the bullpen once Kelly returned. Soroka, who signed with the Diamondbacks this offseason, has started the season with a 3-0 record, pitching a 2.87 ERA in 15.2 innings.

All things considered, it’s more than likely that Kelly will take right-hander Brandon Pfaadt’s spot in the rotation, based on the first group of starts from the Diamondbacks’ rotation. This means that Pfaadt will either be moved to the bullpen as a long reliever or sent down to Triple-A Reno. The latter would be a drastic move, but based on the current roster, there’s not many options for the Diamondbacks.

Pfaadt has struggled in his first three starts of the season, posting a 5.94 ERA, which is fifth-worst in the majors among qualified pitchers, and giving up 12 total runs.  

His most recent start against the Phillies saw the Diamondbacks’ first loss with him on the mound after he yielded back-to-back home runs to Kyle Schwarber and Bryce Harper in the third inning at Citizens Bank Park. 

The biggest problem Pfaadt has faced in the last few seasons is poor performance late in games, particularly the third time through the order. 

During the first time through the order this season, Pfaadt has a 2.70 ERA and has yielded only five hits and one walk. After that, Pfaadt’s ERA balloons to 8.38. He has given up 10 runs, 12 hits and five walks after one time through the order. 

The Diamondbacks agreed to a five-year, $45 million contract extension with the now-27-year-old in March 2025. Since that extension, Pfaadt has a 13-10 record with a 5.31 ERA.

Another ripple effect of Kelly’s return is the pushback of left-hander Eduardo Rodriguez’s next start, which is now scheduled for Wednesday. 

Rodriguez is off to a fast start to his season, pitching lights-out in his first three starts, dealing a 0.50 ERA with 11 strikeouts in 18 innings. The Venezuelan has seen great success with his offspeed pitches, ranking in the 99th percentile among MLB pitchers according to Baseball Savant.

Kelly, a former Arizona State player, returned to the Diamondbacks this offseason, signing a two-year, $40 million contract in December.  He was traded to the Texas Rangers at the 2025 MLB trade deadline for pitchers Kohl Drake, Mitch Bratt and David Hagaman.

Kelly was named the Opening Day starter earlier in spring training. However, after suffering a back injury, the 37-year-old pitcher’s 2026 debut was delayed and Zac Gallen got the ball in the opener.

Although there was pressure for Kelly to return to action as soon as possible, Lovullo knew that it was smart for the Diamondbacks to take their time, especially given Kelly’s injury history. 

“We want to see him go out there and work, and work successfully,” Lovullo said. 

Although the lifelong dream of getting the Opening Day nod was taken away from Kelly, the main concern for him was getting back to being 100% as soon as he could.

“I had a little bit of a conversation with Merrill on that,” Lovullo said after announcing the news of the injury. “All he wants to do is get healthy.”

Kelly is scheduled to go against Baltimore’s left-hander Trevor Rogers, who is 2-0 to start the season with a 1.89 ERA in 19.0 innings pitched. 

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