The Diamondbacks transferred Frias' (shoulder) rehab assignment to Triple-A Reno on Tuesday.
Frias has been on Arizona's injured list since April 19 with right shoulder inflammation but finally looks to be inching toward a return to the active roster. He began his rehab assignment in the rookie-level Arizona Complex League over the weekend, tossing a scoreless inning in his lone outing. He'll likely make a handful of relief appearances for Reno before rejoining the big-league bullpen.