Yilber Díaz

The Arizona Diamondbacks are calling up right-handed pitching prospect Yilber Diaz from Triple-A Reno on Friday to replace right-hander Ryne Nelson (forearm) on the active MLB roster after he was diagnosed with a partially torn flexor tendon in his forearm, according to Arizona Sports' John Gambadoro. Diaz, the team's No. 22 prospect per MLB Pipeline, will return to the big leagues after posting a 4.31 ERA (4.57 FIP), 1.47 WHIP, and 20:15 K:BB in 31 1/3 innings over eight appearances (four starts) in his first two years in the league in 2024 and 2025. The 25-year-old Venezuelan returns to Arizona after going 3-3 with a 4.50 ERA, 1.66 WHIP, four saves, and a 43:21 K:BB in 32 innings in 26 relief appearances at Reno in 2026. Since he has made a full-time move to a relief role this year, fantasy managers should steer clear of Diaz for now. It's unclear exactly who will take Nelson's rotation spot in the desert, but it will most likely be Brandon Pfaadt.