I know -- we are here to speculate. My point is we should leave some room for player development, and recognize that our guesses aren't infallible.
Often posters predict exactly how many minutes each player will get, and who won't play at all. They are often wrong. Before 2010-11, many posters were sure that the 7.0 rotation in league play would have no room for CJ and Keita, not recognizing that JB would play 8 and 9, and CJ was better than advertized. Last year, people knew that BT and Scoop would each play 30 minutes, not recognizing that Dion had upside and could change his attitude more easily than BT could add to his skills.
My guess is that Grant has a well-rounded game that might fit a need. CJ is comfortable working inside, and trying to take his game to SF. Rak is trying to build some skills. Southerland is a 3 pt shooter, trying to round out his game, but not much of a passer and hasn't shown he can dribble-drive. There is opportunity for Grant and the forward rotations are far from settled.