It's hard to make bets on bench players as our team hasn't been finalized yet (16 players now) and no guarantee of who gets cut first. Keeping Darius Miles to me just makes sense, has I think he's a better SF than lets say Pruitt is a PG. Assuming that Ainge cuts or trades Pruitt, then our team would be...
Rondo,Cassell,House
Ray,Tony,Giddens
Pierce,Miles,Scalabrine
KG,Powe,BWalker
Perk,Pat0,BBD
So in there outside of our starting 5, the next guy on the court will naturally be a big, since they can't take on as many minutes and tend to get into foul trouble earlier. As for the offense being ran, I see Sam taking on that role and House being strictly a shooter. The sad part to me is that I expect to see Tony Allen taking on minutes at SF even with Miles, for games where teams go small and the big 3 are resting. There we'd see something like Sam,House,Tony,Miles,Powe. Sam will do better this year with team chemistry/experience will aid his game.
As for the rookies, I can't fairly judge them and there roles, but I'd expect to see them get more minutes than Scalabrine either way.
My bet is that Ainge will package Pruitt/Scalabrine in a trade for any 6'11/7 footer he can find.