The Twins optioned Ober to Triple-A St. Paul on Monday, Do-Hyoung Park of MLB.com reports.
Ober earned a victory in his first start of the season Sunday against the Nationals by allowing only one run and striking out four over 5.2 frames. He'll return to the minor leagues with Kenta Maeda (ankle) on track to make his next turn through the rotation Wednesday versus the Yankees. The Twins are expected to make a corresponding move Tuesday, per Park.