Pirates Prospects reports that pitching prospect Clay Holmes will visit Dr. James Andrews to have his elbow examined. That doesn't necessarily mean he'll have surgery, but pitchers don't go to Dr. Andrews to talk to him about about how healthy they're feeling.
The Pirates drafted Holmes out of high school in 2011, then paid him a record amount for a ninth-round pick in their apocalyptic draft spending binge before MLB changed the rules regarding signing bonuses. Holmes hasn't gotten great results since being drafted, but he steadily improved as the 2013 season went along, and he's still a big guy who gets ground balls and has good stuff.
He only pitched 119 innings last season, so if he's hurt, that's probably not the reason. The Pirates have recently done a very good job keeping their top pitching prospects healthy, so much so that it's actually pretty jarring to hear that one of their prospects might have a major injury.