McCaughan was outrighted to Triple-A Tacoma on Friday.
McCaughan appeared in two games for the Mariners in late July and spend the rest of the season at the Triple-A level. He posted a 4.53 ERA, 1.11 WHIP and 99:17 K:BB over 115.1 innings for Tacoma and has now been removed from the 40-man roster heading into the offseason.