The Mariners optioned McCaughan to Triple-A Tacoma on Wednesday.
Seattle called McCaughan up from Tacoma on Monday, but he wasn't needed out of the bullpen for either of the first two games of the Mariners' series in San Francisco. Though McCaughan appeared to be a candidate to fill in for the injured Bryce Miller (finger) in Wednesday's series finale, the Mariners instead opted to call up Tommy Milone from Tacoma to make a spot start.