McMahon was in the lineup batting seventh and playing second base against the Cincinnati Reds on Saturday night.
McMahon made Colorado's opening day roster but was optioned on May 1 after batting .180 in 28 games (11 starts). He hit .253 with three home runs and 16 RBI in 22 games for Albuquerque.
Valaika also began the season with the Rockies before being optioned on May 8. He was recalled six days later and hit .176 in nine games for the Rockies.
Colorado has a full 40-man roster.