The Padres optioned Mazur to Triple-A El Paso on Saturday.
Mazur only lasted 2.2 innings during his start Friday against Baltimore, allowing one earned run on two hits and two walks in the process. The Padres won't need to use a fifth starter for another two weeks, so they'll send down the struggling right-hander in favor of Alek Jacob, who will provide the bullpen with another fresh arm.