Glenn Stewart plays traditionally as a second row though. Watmough plays more of the Lock position for the Sea Eagles, in the middle of the park.
Gidley could easily play a second row type role though. There are many in the NRL that dont have much of a defensive workload (Mateo, Williams, Lewis, Gallen - when strictly on the edge, and many more).
Problem is Gidley likes to get involved, its just his nature. In the halves he normally gets 20-30 tackles, and I doubt thats because teams target him, as he is one of the best halves defenders, with one of the biggest motors in the game, so you arent going to tire him.
So playing as a second rower (or at least defending there) he is more likely to put up Housten like numbers, than McKinnon like numbers.
The other problem is we have Beau Scott, Housten and McKinnon on the books for next year. All 80 minute fringe players. And the signing of Smith all but rules out a move into the centre for Housten.
Gidley will almost certainly be halfback next year. And the best case scenario for Roberts is a bench position, and playing a similar role as he did last year in the wins over Canberra and the Sharks where he played 45-50minutes, and Gidley went to hooker.