The Guardians sent Holderman (wrist) to Triple-A Columbus on Thursday for a rehab assignment.
Holderman has been out with right wrist inflammation since Sept. 4, though he's been battling the injury since mid-August. The right-hander is eligible to return Sept. 19 and would provide a late-season boost for Cleveland's bullpen given his 2.73 ERA through 54 appearances this year.