Brutal A.J. Puk Injury News is Harsh Blow for the Diamondbacks

Another hiccup in a Diamondbacks pitcher's rehab.

Apr 13, 2025; Phoenix, Arizona, USA; Arizona Diamondbacks pitcher A.J. Puk (33) comes in to close in the ninth inning against the Milwaukee Brewers at Chase Field. Mandatory Credit: Allan Henry-Imagn Images | Allan Henry-Imagn Images

The latest injury news on Arizona Diamondbacks' rehabbing left-hander A.J. Puk is not positive.

According to a report from AZCentral's Nick Piecoro, Puk — who was working his way back from the internal brace variation of Tommy John Surgery — will have to pause his rehab with what is being described as left shoulder discomfort. Puk will have to undergo an MRI.

This news is especially concerning, given the fact that right-handed ace Corbin Burnes is dealing with a notable setback in his own rehab after he suffered a strain to the teres major in his right shoulder. Burnes' timeline was pushed back to around September (optimistically speaking).

"We're going to get some MRIs, and we're going to get the diagnosis as soon as possible," manager Torey Lovullo said (via Arizona Sports 98.7's Burns & Gambo show). "When it's a complete diagnosis, I'll let you guys know.

"But being pulled back, it's not going to be a couple days. It's going to be a couple weeks at least," Lovullo noted.

Diamondbacks' A.J. Puk may have suffered setback

Apr 17, 2025; Miami, Florida, USA; Arizona Diamondbacks catcher Jose Herrera (11) and pitcher A.J. Puk (33) celebrate a win over the Miami Marlins at loanDepot Park. Mandatory Credit: Jim Rassol-Imagn Images | Jim Rassol-Imagn Images

Puk, 31, has not pitched in a game for the Diamondbacks since April 17 of 2025. He's been working his way back from surgery at a solid pace, and was already on a rehab assignment in Triple-A Reno, where he was displaying sturdy velocity, hitting 96 MPH on his four-seam fastball.

Puk had appeared in three Arizona Complex League games and two Triple-A contests. He was expected to get into seven or eight rehab outings, rather than rushing back.

It had also been previously reported that Puk would have a "planned minor pullback" in his rehab, with a bullpen scheduled for the weekend. Instead, he'll have to pause his process entirely for the moment.

Puk was on track to be the first of the three Tommy John surgery recipients to make his return. Initially, an early- or mid-June return was likely. At this stage, Puk may not be back until around the All-Star Break, though depending on the severity of this new issue he could end up on a similar timeline to Burnes.

"I know he wants to be here," Lovullo said. "The fact that he's able to pull back and say that he felt a little bit of shoulder discomfort, to me, in my opinion, is what being a D-back is all about. So we're just going to pull back on this, it's left shoulder discomfort. We're not exactly sure of the extent of it."

The Diamondbacks' bullpen has, perhaps surprisingly, performed above expectations this season, despite missing Puk and co-closer Justin Martinez. Arizona has only one left-handed reliever on the roster currently in Brandyn Garcia, who had a rough game Tuesday, but holds a 3.07 ERA in 13.2 innings.