Yeah, he injured his foot at Round Rock. Not really clear on the injury, but Richard Fitts had the exact same injury happen the next day. I've heard it was related to the big toe, and neither could really push off their back foot without severe discomfort. And several have blamed Under Armour cleats for it. Josh Hall has also dealt with a foot injury and an ankle injury.
But back to Greenhill, he battled the foot injury, made adjustments to pitch effectively around it (mainly going to more offspeed pitches), but in doing so and then trying to transition back to the bullpen, he's picked up a shoulder injury, most likely for compensating around the foot injury. Honestly, I'd be surprised if we saw him pitch again at Auburn. Maybe he throws Tuesday in Hoover if we need him, but he's not really practiced much or thrown much in the last 2-3 weeks.
As an aside, Jack Owen will start in Hoover on Tuesday.