The Diamondbacks recalled Frias from Triple-A Reno on Wednesday.
He'll take the spot in the bullpen that previously belonged to Edwin Uceta, who was optioned to Reno after throwing three innings in long relief in Game 2 of Tuesday's doubleheader with the Dodgers. Frias, who most recently tossed two innings Sunday for Reno, will give the Diamondbacks a fresh relief arm for Wednesday's series finale.