The Blue Jays optioned Mayza to Triple-A Buffalo following Sunday's 13-3 win over the Orioles, John Lott of The Athletic Toronto reports.
His demotion clears a spot on the active roster for Preston Guilmet, whom the Blue Jays scooped up off the waiver wire a day earlier. Mayza covered the final two innings of Sunday's rout, giving up no runs and only one hit to lower his season ERA to 2.70.