Mlodzinski has been unavailable lately due to right forearm tightness, Jason Mackey of the Pittsburgh Post-Gazette reports.
Mlodzinski's last Grapefruit League appearance came more than a week ago and he allowed five runs while recording just two outs in that outing. The reliever has made nice recent progress, though, as he's throwing out to 120 feet and is slated for a bullpen session within the next few days. It would appear Opening Day is still possible, but it will be close.