Diamondbacks Release Young Reliever

Montes De Oca pitched to a 4.07 ERA in 17 appearances for the Reno Aces in 2025 — a number that is considered significantly above-average for such an offense-heavy environment. He struck out 26 batters in 24.1 innings thanks to his upper-90s arsenal.

Those numbers earned him a call-up on May 16, but he did not get into a game in his first stint with the MLB club.

He was optioned back, and eventually recalled on June 7, where he finally made his big league debut. Montes De Oca pitched 2.2 impressive innings of scoreless relief and picked up his first 2 MLB strikeouts.

But Montes De Oca would lose the rest of 2025 to injury, having surgery on his lower back. He also reported elbow discomfort at the time and underwent an MRI.

It's possible Montes De Oca returns on a minor league deal at some point, although he did not appear to be in Arizona's plans for their 2026 bullpen.

With Montes De Oca out of the organization, the D-backs will lose some depth, although they do already have quite a large pool of arms to pull from should they suffer more attrition in 2026.

The D-backs have a large group of relievers — some young, some veteran — on the bubble this spring looking to crack the major league roster at some point in the 2026 season.

With closer options Justin Martinez and A.J. Puk both out for significant time recovering from Tommy John surgery, Arizona's closer committee is an open competition, led by the likes of Kevin Ginkel, Ryan Thompson and a returning Paul Sewald.

"What I've told every single one of them is there's eight spots open, and you've got to go out there and earn it," manager Torey Lovullo said of his relief group.

"I want you to have that earning mentality. Nothing's going to be handed to you. How it sits and where it goes, I don't know what that answer is."