Dunning was used in relief in Saturday's 13-5 loss to the Guardians, tossing one inning while allowing one earned run on two hits.
Dunning had started in both of his previous two appearances, but he looks set to operate as a reliever moving forward with the Rangers expected to call up Jack Leiter from Triple-A Round Rock during the upcoming week to serve as a temporary fifth member of the rotation until at least one of Tyler Mahle (shoulder), Jacob deGrom (elbow) or Max Scherzer (shoulder) returns from the injured list. In his last start Monday against the Pirates, Dunning averaged just 88.1 miles per hour with his fastball, and he didn't notice much of a bump in velocity Saturday despite moving to the bullpen. He maxed out at 90.3 mph and failed to generate a swinging strike from any of the four batters he faced.