The Pirates placed Mlodzinksi on the restricted list Sunday.
The official reasoning for the move hasn't been disclosed, but it's unlikely to be a coincidence that it comes just a few days after Mlodzinski was bumped from the starting rotation to the bullpen. The right-hander has a 3.76 ERA across 55 innings this season, though his 1.42 WHIP and 46:20 K:BB paint a less encouraging picture of his performance.