Sims was placed on the 15-day injured list with low back spasms Thursday, retroactive to May 11.
The 28-year-old spent the first few weeks of the season on the injured list due to an elbow injury, and he'll now be sidelined with a back issue. Over his six appearances this season, the right-hander has picked up a win and a save while posting a 9.45 ERA and 1.65 WHIP in 6.2 innings. Art Warren, Tony Santillan and Hunter Strickland are the favorites for save chances while Sims is sidelined. It's not yet clear when Sims will be able to return to game action.