I know that the McAvoys seem to be stuck in the depth chart behind other young guys, but they are still only RS-FR. A lot can change in 3+ years.
As far as Heifort, I've heard nothing but good things about him. He's a kid who they think is going to get pretty big and my guess is that he's earned his PT. I think they wanted to get both him and Marek some PT. I didn't see Foster Bush play, I might have missed that.