Previewing the Arizona Diamondbacks Rotation

Spring training has come to a close, and while fans prepare for opening day, the Arizona Diamondbacks' front office is still in the midst of some chalenging roster decisions.

In previous installments of our depth previews, we have already tackled the infield, outfield, and catcher groups, all of which will be linked at the bottom of the story. Next in line is the D-backs' myriad of starting pitching which may just be the best in baseball.

Rotation

Corbin Burnes - RHP

After inking a $210 million contract this winter it shouldn't be a shock that Burnes is viewed as the clubs new ace starter. The right-hander is not only a former Cy Young winner, back in 2021, but has made four consecutive All-Star games, and has garnered Cy Young votes in each of the last five seasons.

There are few pitchers worth handing out such a large contract to, but he certainly fits the bill, even giving out a minor hometown discount. He has finished with an ERA below three in five of his seven major league campaigns, including 2024, and has only posted an ERA+ below 127 once.

Likely a top five starter in all of baseball entering 2025, he will headline the Diamondbacks' rotation this season, and for years to come. Burnes will be making the fifth start of the season for the Diamondbacks due to needing to stay on regular rest.

Related Content: Corbin Burnes Tells All in Q&A on Rotation Order Situation

Zac Gallen - RHP

The Diamondbacks' ace for years, Gallen is entering his final season before free agency. In a sentimental decision, Torey Lovullo tabbed Gallen to be the opening day starter. The right-hander is coming off a somewhat injury riddled 2024 season where he battled hamstring issues that relegated him to 148 innings pitched.

Still, he is only a season sepearated from a strong 2023 campaign where he started for the National League in the All-Star game. He has received Cy Young votes in three of the last five seasons and even received down-ballot MVP votes in 2023.

While he has been the D-backs' most dominant arm during his tenure, he has also experienced his share of struggles. 2024 saw Gallen have issues with fastball command, something which had been a strength for him as a pitcher throughout his career. He will need to see a rebound in command in 2025 if he hopes to return to his Cy Young caliber form.

Merrill Kelly - RHP

Kelly missed substantial time in 2024 due to a right-shoulder strain. While his numbers last year look pedestrian, with a 104 ERA+ in a 73.2 inning sample, he is coming off incredible seasons in 2022 and 2023.

The righty pitched to a 4.70 ERA in 15.1 innings this spring but saw a return to form in his strikeouts with 9.4 K/9. Now guaranteed extra protection in the rotation and hopeful for a healthy season, Kelly will need a big rebound in his contract year.

Eduardo Rodriguez - LHP

The lone lefty in the Diamondbacks' rotation, Rodriguez is in a similar boat to Kelly and Gallen. His 2024 season was stunted by a left shoulder strain, leaving him only available to pitch in 50 innings during his inaugural D-backs season.

Still, he is only one season removed from being one of the most dominant southpaws in the American League. Rodriguez posted a 3.30 ERA across 152.2 innings with Detroit in 2023, totaling a 131 ERA+.

Concern does lie in the fact that the lefty has now gone three consecutive seasons averaging less than one strikeout per inning spanning a seasons length. This is something that he seems to have rebounded on to some extent, with 10.8 K/9 across 10 spring training innings, but it will still be an important issue to monitor.

Brandon Pfaadt - RHP

The lone young starter in the rotation is Brandon Pfaadt. In 2024 he was easily the most durable Diamondbacks pitcher, posting more innings than any other starter with 181.2.

He also happened to be one of the most unlucky pitchers in all of baseball, with a 3.61 FIP compared to his inflated 4.71 ERA, a pattern that was similarily shared in his 2023 rookie season. While his surface numbers might not do him justice, he did see improvement in other aspects of his game.

The righty managed to limit walks to an incredible extent, allowing only 2.1 BB/9, an improvement from his 2.4 the year prior. He did so while also raising his strikeout rate over the much larger sample, now averaging 9.2 K/9 in 2024.

Pfaadt will need to limit location mistakes on his trademark sweeper. Batters hit just .215 against the pitch, and the WHIFF rates was 36%. But he tended to leave it in the middle of the zone at times, resulting in 13 of the 24 homers he allowed coming off the Sweeper.

MLB Depth

Other rotation arms that will work as current MLB depth are Ryne Nelson and Jordan Montgomery.

Nelson was arguably Arizona's best starter in 2024's second half, but left something to be desired this spring, and lost out on a rotation spot due to the incredible roster crunch. According to Diamondbacks ON SI's Jack Sommers, he will likely work out of the bullpen to start the year.

Montgomery was the D-backs' prize acquisition entering 2024, but struggled massively throughout the entire season. Things havent gotten better this spring, with a 15.00 ERA in 3 innings thrown. While this is skewed by a particularily bad first outing, he was left out of the rotation for a reason.

There are still plenty of trade rumors regarding Montgomery, and these could very well still come to fruition. Arizona has a strong incentive to seek these out because of the lefty's crippling $22.5 million salary.

40 Man Roster Depth

Other names currently on the Diamondbacks' 40 man roster who could see MLB time in case of injuries include Yilber Diaz, Tommy Henry, and Cristian Mena. All three are in the Triple-A Reno rotation and have MLB experience. Joe Elbis. is also on the 40-man, but will pitch in Double-A Amarillo to start the year, and is likely more than a year away from his MLB Debut.

Diaz, a top pitching prospect in Arizona's system made his debut last season and looked promising. While 2025 might not open the door for him quite yet, 2026 and beyond could give him the room to burst into the club's rotation.

Non-Roster Depth

Yu-Min Lin and Dylan Ray are two very promising young arms in the D-backs' farm system. Both are likely at least a year away as well and will start the year in Double-A Amarillo with the Sod Poodles.

Related Content:

Previewing the Arizona Diamondbacks' Outfield Unit

Previewing the Arizona Diamondbacks Infield

Previewing the Arizona Diamondbacks Catchers

Arizona Diamondbacks 2025 Player Projections Links Hub