This is difficult because pleasant surprise means off-the-radar or written off due to past poor performance and/or multiple injuries.
That would rule out players like Butler, Manny Rugumba, Lattimore, etc. because there's already expectations for them or they've flashed already.
I think Gervase could be one because of his situation starting due to Synder's injury and having not played any meaningful regular season snaps yet. Someone listed Bower and actually that would surprise me if he had an outstanding season. Easley was listed and I think that fits as a surprise. Maybe not a shocker given his JUCO background but a surprise if he's a strong contributor.
Players like Mansell, Boyle would fit as no one expects them to contribute this year. Possibly Weigers as we expect to see Stanley. Maybe the new punter who replaces Coluzzi was did a great job last year. Maybe one of the DTs farther down the depth chart than Lattimore or Reiff. How about Ross Reynolds at guard? To me it's players like this that are surprises if they contribute and play well.