Christian Montes De Oca To Undergo Lower Back Surgery

Just one day after Diamondbacks closer Justin Martinez underwent Tommy John surgery, fans in Arizona received more troubling news about the status of the bullpen when manager Torey Lovullo told reporters (including Alex Weiner of AZ Sports) that right-hander Christian Montes De Oca is set to undergo lower back surgery that could keep him out of commission for the remainder of the 2025 season. Montes De Oca was placed on the injured list earlier this week due to inflammation in his right elbow, but is now ticketed for an unrelated procedure on top of that issue.

It’s a brutal turn of events for the 25-year-old, who made his big league debut just last week and has one scoreless outing of long relief under his belt in the majors at this point. The right-hander looked great in that debut, with zero hits and one walk allowed as he struck out two in 2 2/3 innings of work. It appears that may be his only appearance in his debut season unless he’s able to both overcome the elbow inflammation he’s been battling and his upcoming back surgery in time to get back on the mound for the Diamondbacks before the end of the year. If there’s a silver lining in the announcement, it’s that Montes De Oca will be able to try and address both issues at once rather than dealing with multiple prolonged layoffs.

Montes De Oca signed with Arizona out of the Dominican Republic and made his pro debut during his age-22 season back in 2022. A pure relief prospect from the jump who has never started a game as a pro, Montes De Oca nonetheless moved through the Arizona system quite quickly. He began his second pro season at the Double-A level and spent barely any time at Double-A in his third pro season before making the jump to Triple-A. He struggled in that first taste of the Pacific Coast League last year, but in 2025 he managed a solid 4.07 ERA and 3.66 FIP with a 25.5% strikeout rate and a walk rate of just 5.9%.

Montes De Oca joins Martinez, A.J. Puk, Corbin Burnes, Jordan Montgomery, Blake Walston, and Cristian Mena on a rapidly growing list of Diamondbacks pitchers facing extended absences. Impressive rotation depth has allowed them to weather the storm in terms of starting pitching, but the club’s relief depth has been whittled down to the point where closer Shelby Miller and lefty Jalen Beeks are the only two reliable leverage arms at Lovullo’s disposal until another option emerges internally, an external addition is made, or Puk returns from his own bout of elbow inflammation. Pitching woes are a major piece of what’s left Arizona 3.5 games out of a Wild Card spot, although the club remains one game over .500 and could theoretically look to shore up its pitching depth this summer if the team’s internal options can keep them in the race until trade season begins in earnest.