Sims was recalled from Triple-A Louisville on Saturday.
Sims was part of a three-player package acquired from the Braves in exchange for Adam Duvall in July. The Reds want to see how he fares in the majors over the final month of the season after posting a solid 3.81 ERA and 32:5 K:BB across five starts with the Bats following the trade. At this point, it's unclear if the right-hander will work in long relief or if he'll get a chance to start for the out-of-contention Reds. Sims owns a career 5.96 ERA across 68 big-league innings over the past two seasons.