Zac Gallen Pulled from Mexico City Start After Being Struck by Ball

This is concerning.

Apr 12, 2026; Philadelphia, Pennsylvania, USA; Arizona Diamondbacks starting pitcher Zac Gallen (23) throws a pitch against the Philadelphia Phillies in the first inning at Citizens Bank Park. Mandatory Credit: Kyle Ross-Imagn Images | Kyle Ross-Imagn Images

Arizona Diamondbacks right-hander Zac Gallen was removed from his start against the San Diego Padres in Mexico City after just three scoreless innings on Saturday after he was struck by a comebacker during the third frame.

In his place, right-hander Brandon Pfaadt will take over. This will be Pfaadt's second relief appearance since transitioning to a bullpen role. His first effort was a 6.1-inning, one-run affair. Pfaadt threw a scoreless fourth inning immediately upon entering.

The Diamondbacks led 4-0 after a two-run double by Jose Fernandez and a two-run homer by Alek Thomas Of course, the concern is now for Gallen's health.

The Diamondbacks have since announced that it is a right shoulder contusion for Gallen. A contusion is, in essence, a bruise, of varying severity.

This initial diagnosis could mean Arizona has avoided potential disaster, but it is still unknown whether or not Gallen will require further testing. A more severe issue is still within possibility, for the time being.

Diamondbacks' Zac Gallen pulled after comebacker

Apr 1, 2026; Phoenix, Arizona, USA; Arizona Diamondbacks pitcher Zac Gallen in the second inning against the Detroit Tigers at Chase Field. Mandatory Credit: Mark J. Rebilas-Imagn Images | Mark J. Rebilas-Imagn Images

Gallen had been cruising through his start, looking surprisingly sharp in the high-elevation environment that is Mexico City. With one out, Padres catcher Freddy Fermin hit a 92 MPH line drive right back at Gallen, who deflected it with what appeared to be his throwing (right) shoulder.

After a lengthy conversation with trainers and manager Torey Lovullo, Gallen stayed in the game to finish the inning. He shut down the third without further damage, and did not appear to be in severe pain.

But Pfaadt was seen warming up not long after. It is unclear as of this writing whether this move was made for cautionary reasons only or if a more severe issue will lie beneath the surface.

Gallen has been in the midst of a puzzling season. Though his underlying metrics have not looked favorable, he's delivered some high-quality outings, owning a 3.14 ERA after his three scoreless frames on Saturday afternoon.

If the D-backs are in danger of losing their former ace for any amount of extended time, they do have the luxury of slotting a still-stretched-out Pfaadt back into the rotation as long as needed.

Though Pfaadt has not necessarily had the most impressive season in terms of numbers, he does provide rotation depth. As the saying goes, a team can never have enough starting pitching depth, an the D-backs do have that, for now.

Arizona Diamondbacks On SI will continue to report on this developing story.