First of all, can we all cut the BS scrum references which mean very little now - there are no such things as locks, second rowers and front rowers & hookers any more - there are edge forwards, middle forwards, props & acting halves. In particular, a player numbered as a lock or second row doesn't tell us where they are on the field.
re Sutton, I wouldn't say that the middle forward has to be an 80 minute player. 60 minutes is a great return. he is primarily attacking and definitely defending between the scrum hash marks now so will go through a lot more work tackling and colliding with bigger players then he ever has. There are very few freaks at that position that play 80 minutes (such as Gallen) and I'd say that those that play as middle forwards and props that don't get a spell for some minutes lose their effectiveness and impact.
with the 4 prop rotation of Sam, George, Tom & one of Tyrell, Luke B, Clark & Neale to be the battering rams up the middle, Sutton can be interchanged primarily with Lowe & Picker as the agile middle forwards. there is no requirement for Sutton to be on the field all the time, and he shouldn't be in his new role.