I think the starters are set, as everyone has said. Agree with
@husky429 that Castle probably draws the 3 on defense. Newton could take 1 or 2. I think that's matchup driven, the PG or SG could be the more athletic player. Diarra would usually have the quickest guard when he's in.
Bench, I think Johnson gets the most minutes overall at 4-5. I don't see Donovan logging as many minutes as Sanogo did. I think it's a battle on the wings between Ball, Ross & Stewart. One of them will emerge to be the primary backup 2-3.
Diarra the main backup PG, but Castle could play there too, with Cam & a freshman. Roumoglou is a big question mark, but I wouldn't rule him out at the SF spot. I expect Singare to play sparingly, mostly early in the season.