D-backs' Rotation Was Struggling Before the Corbin Burnes Injury

Oftentimes in baseball when a team suffers a key injury or two, those injuries will be held up as examples for why a team underperformed. Sometimes that's an accurate depiction, but in the case of the Arizona Diamondbacks' starting rotation, something important needs to be pointed out as the team and its fanbase await the results of Corbin Burnes' MRI on his right elbow.

That is the fact the D-backs' starting pitchers' ERA of 4.51 ranks 25th in MLB and is well above the league average 3.99. There should be no revisionist history when the story of the 2025 is retold. The rotation was already struggling with underperformance as a unit even before the injuries to Burnes and Eduardo Rodriguez.

Diamondbacks Starting Pitchers Ranked by ERA | Jack Sommer

It wasn't supposed to be this way. During the preseason almost every pundit (including me) projected the D-backs to have a top 10 rotation in MLB. After all they added Burnes to the already strong core of Zac Gallen, Merrill Kelly, Brandon Pfaadt, Eduardo Rodriguez, and the emergent Ryne Nelson.

But the results have simply not been there for too many innings. Burnes was doing quite well over the last month and Merrill Kelly has just two bad starts that blew up his ERA a bit, but it's still well below 4.00, better than the 4.03 that FanGraphs projected for him.

But Zac Gallen has had a miserable season so far across the board. His walk, strikeout, and home run rates are the worst of his career. That, along with a little bad luck has him sporting an ugly 5.54 ERA. Gallen will be a free agent at the end of 2025, and certainly didn't envision these types of struggles heading into his walk year.

Rodriguez has never looked like the pitcher the D-backs signed prior to the 2024 season. The early narrative was that he was pitching into a lot of bad luck, and that was certainly true in several of his outings. But on the whole, he simply has not been able to suppress runs at any point in his Diamondbacks career. He has a 5.99 ERA in 19 starts since August of 2024 and is now on his second injured list stint.

Brandon Pfaadt walked a high wire for much of the season, striking out fewer batters than he had in the past while allowing a lot of hard contact. He went into his last start with a decent 3.90 ERA, but a 4.92 FIP (Fielding Independent Pitching).

He came out of it with a 5.05 ERA and 5.02 FIP after failing to record an out and giving up eight runs. His xERA from Statcast, which measures quality of contact against along with actual walks and strikeouts, is a concerning 6.71.

Meanwhile, the starter that has produced the best results for the team since July of last year, Ryne Nelson, was relegated to a long relief swing-man role due to the number of veterans in the rotation and the contracts they're under. Team officials will deny that contracts play a role in deciding who is in or out of the rotation, but those statements simply don't pass the smell test.

Just before the Burnes injury, Nelson was informed he was going back to the bullpen to make way for Rodriguez, who is nearing his return. That highly-questionable decision was explored here on the pages of this website.

Then potential disaster struck when Burnes called the trainer out and told him he'd suffered an elbow injury. While we await news to find out of if the worst has been avoided, which may be the case, it still seems likely that Burnes will need a stint on the injured list regardless.

According to Arizona Sports 98.7's John Gambadoro, Burnes' initial MRI results were inconclusive, and the ace will get a second opinion, with new info likely to come Thursday or Friday.

Should know more on Corbin Burnes Thursday or Friday. The Dbacks ace is getting a second opinion on his right elbow after initial tests were inconclusive
— John Gambadoro (@Gambo987) June 3, 2025

For all the struggles of the rotation, the bullpen has been even worse of course, posting a 5.28 ERA, which ranks 26th in the league. While the A.J. Puk injury is often pointed to as a key turning point for the bullpen, it's also true that the pen should not have fallen apart due to one major injury.

All of this poor run prevention has negated one of the top performing offenses in the league. The D-backs are fifth in runs scored per game (5.02), but are 26 in runs allowed per game (5.19).

If Burnes misses any signifcant amount of time, then presumably Nelson will be a starter, but as of this writing we just don't know the team's decision on this point. Another starting option includes Cristian Mena, who was just recalled to provide long relief coverage over the weekend. Beyond Nelson and Mena, there is Bryce Jarvis, who has been starting in AAA and just won PCL pitcher of the week.

UPDATE: Gambadoro posted that Burnes will indeed go on the 15-day IL and Nelson will remain in the rotation. Tommy Henry is being called up to provide coverage in the bullpen.

Corbin Burnes to the 15-day IL. Tommy Henry up with the team to fill a bullpen role. Ryne Nelson back to the rotation.
— John Gambadoro (@Gambo987) June 3, 2025

Where things go from here is anybody's guess. Perhaps Burnes' injury turns out to not be too serious and he is back in not too long a time no worse for wear. Maybe Gallen starts pitching well again, and Nelson stays in the rotation and continues posting a low ERA. Maybe Pfaadt figures out how to keep hitters off the barrel of the bat. And maybe Rodriguez finally starts living up to his contract. Maybe.

D-backs' Rotation Was Struggling Before the Corbin Burnes Injury

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