The Reds optioned Mey to Triple-A Louisville on Sunday.
Mey was recalled from Louisville on Tuesday and got into one game during his latest stint with the Reds, allowing two runs on three walks, a hit batsman and one hit over one-third of an inning versus St. Louis on Friday. He'll now return to the minors in order to clear a spot on the 26-man active roster for Rhett Lowder (shoulder), who was activated from the injured list in a corresponding move.