I went Walker, Tatum, Smart.
I think Walker and Tatum should be locks, Smart has come into a situation where the final two spots are up for grabs. There aren't too many shooting guards in camp so he has a shot as the utility guard on the team.
Brown could have a shout if they were looking for someone more explosive but I think they'll go for Smart to build intensity in the scrimmages.
Edit: Just read you guys saying Lowry might pull out which makes Smart the 4th guard. Still don't think that brings Brown onto the roster but he's one step closer