Feltner was optioned to Triple-A Albuquerque on Sunday, Patrick Lyons of TheDNVR.com reports.
Feltner made a spot start against the Phillies on Wednesday and allowed four runs on seven hits and two walks while striking out seven in five innings to take the loss. The righty will head back to the minors as part of a move to trim the major-league roster to 26 players by Monday.