The Angels optioned Mederos to Double-A Rocket City on Wednesday.
Mederos' stay with the big club lasted just one day, with the young right-hander tossing a scoreless inning out of the bullpen in Tuesday's 5-1 loss to Atlanta. He'll cede his spot on the 26-man active roster and in the bullpen to right-hander Dominic Leone, whom the Angels acquired from the Mets ahead of Tuesday's trade deadline.