The Diamondbacks outrighted Montes De Oca (back) to Triple-A Reno on Monday.
The transaction frees up a spot on the Diamondbacks' 40-man roster. Montes De Oca is recovering from surgery to repair a stress fracture in his back and it's not clear when he will be ready to pitch again. The reliever tossed 2.2 scoreless frames in his lone appearance for Arizona in 2025 and held a 4.07 ERA and 26:6 K:BB over 24.1 innings at Triple-A Reno.