The only locks are a backcourt of Boat and Purvis. Calhoun and Hamilton will be fighting for who starts as the 3.
Neither Brimah nor Nolan established themselves as a lock for the 5 spot with their play last year. Brimah is coming off surgery and Nolan put on weight. They will fight for the 5. I do believe there is a chance they both play at the 4 and 5 as Facey has never shown that he has a jump shot that can stretch the defense. There ability to play together, however, will depend on what they show in practice.
I think that Facey is likely the 4, but Rock is a dark horse if he really rebounds in practice and shows he can defend his position. Bottom line, none of our bigs have done anything to establish themselves as locks. It will come down to how the perform in practice and exhibitions to determine who starts against Bryant.
My best guess is that on Friday, November 14 we'll have a starting 5 of: Boat, Purvis, Calhoun, Facey and Nolan. As the season progresses, I'm not sure who locks down the 3, 4 & 5, but we'll likely see some different starting 5s over the course of the season.
What really matters most though is which 5 are out on the hardwood at the end of the game.