Oviedo was optioned to Triple-A Memphis on Thursday.
Oviedo started the second game of Wednesday's doubleheader against the Mets and was charged with the loss after he gave up four runs on five hits and no walks while striking out two in four innings. He'll now attempt to sort things out in the minors but could return to the Cardinals as a spot starter at some point. Outfielder Lane Thomas was recalled in a corresponding move.