I think Marquis is pretty much a more natural SG than he is a small forward. He's a SG in the mold of Tony Allen in that he's a pretty decent defensive SG that doesn't have a good shot but can be effective offensively when going to the net. Unlike Allen though, he has a really good handle, is an above average passer, isn't nearly as athletic but makes up for that with actually having a brain and the ability to use it.
Pietrus will be the backup SF, once healthy. Hopefully he is healthy. Marquis will be the backup to Ray Allen. Dooling will be Rondo's backup and Moore, Johnson and Bradley will be getting a ton of court time.....as starters for Portland in the NBDL.
Strangely enough the young player that will probably see the most minutes regularly might be the undrafted, NBDL veteran, free agent, Stiemsma. Not any of the players that actually got drafted.