Minter was optioned to Triple-A Gwinnett on Thursday.
Minter has struggled to a 9.00 ERA, 2.50 WHIP and 4:7 K:BB in six innings since the All-Star break, so he'll head back to the minors for the time being to smooth out some kinks. Chris Martin (back), who was acquired from the Rangers earlier in the week, will take his place on the active roster.