If Sullinger comes in with a completely changed physique -- lighter, quicker, more agile, with the endurance to stay on the floor for 32+ minutes a game -- he will almost certainly have a career year.
All he has to do, really, is be physically fit enough to stay on the floor for 30 minutes or more a night for an entire season. He's been a pretty productive player his whole career.
How realistic is it to expect that, though?