Mack is out of the lineup for Wednesday's game against Atlanta.
After drawing a start against lefty Martin Perez in Tuesday's 8-4 loss, Mack will hit the bench while Atlanta sends another southpaw (Chris Sale) to the hill Wednesday. Liam Hicks will handle catching duties in place of Mack, who is batting .205 with six RBI and six runs through his first 14 games following his May 4 call-up to the majors.