The Mets optioned Muckenhirn to Triple-A Syracuse on Monday.
Muckenhirn was up with the Mets for just one day, as he served as the team's 27th man for Sunday's doubleheader with the Nationals. The left-hander appeared out of the bullpen in the Mets' 8-2 win in Game 2, working two innings while giving up one run on four hits and one walk.