Mayfield was designated for assignment by the Angels on Sunday.
Mayfield was sent down by the Angels on June 19, and he'll lose his spot on the 40-man roster after the team traded for Touki Toussaint on Sunday. Over 24 Triple-A appearances this year, Mayfield has slashed .200/.255/.340 with two homers, 14 RBI, 11 runs and two stolen bases.