Grimm was placed on the 10-day disabled list Tuesday with lower-back stiffness.
It's unclear when Grimm picked up the injury, but it could help explain his recent struggles. Over his last five outings, Grimm has allowed 16 runs over just 2.2 innings of work, walking eight batters while striking out just two. He'll get some time off to recover, though it's unclear when exactly he'll be ready to return at this point. In the meantime, Eric Stout was recalled from Triple-A Omaha in a corresponding move and will take Grimm's spot in the bullpen.