I'm usually slower to criticize walk on dudes who are volunteering their time and effort with virtually nothing in return. At least scholarship guys get school paid for out of the deal.
The point of my comment was just to point out that yes he's not very good, and should not be on the field. But it's not his fault he's playing significant minutes at the D1 level. It's the coaches fault for not being able to recruit a scholarship player to that position that can play over him.