I strongly agree with your first point that Christmas looked a lot better at center than he did at the 4 last year. By the ncaa's, Roc looked pretty good at center, and that was him with practicing and playing at the 4 most of the year. If he was that good with limited experience at center, imagine how good he could be if he's actually able to spend time in practice at center before the season starts there. And since the center spot is the most critical on our team to anchor the defense, I really like the idea of Christmas getting a lot of time there. This might be why JB was just speculating that he thought Coleman might be able to play the 4 since he moves well for a big man, and he also added that we could really use his rebounding on the weak side. (Not to mention I like having Christmas' shot blocking skills at center.) If Coleman is able to lose some weight and improve his conditioning over the summer, this might be our best bet. it's good to hear that JB is at least open to the idea. If Coleman struggles to guard out to the 3 pt line though, which seems likely, then we might have to start christmas at the 4 again, which is not ideal, because based on how raw he looked at the 4 last year, it'll probably take him til his junior year before he really becomes an assett at that position. I think in that case, it's unfair to expect Coleman to be a dominant defender right away at center - it always takes bigs a little longer to develop, and that seems particularly true for SU players at center. And so if Christmas doesn't come back greatly improved at the 4, which he probably won't, and if Coleman takes a little time to learn to play center for JB, which is likely, then starting Christmas at the 4 and Coleman at the 5 might not be a great situation, at least early in the season. So i wouldn't be surprised to see Coleman starting at center, Christmas starting at the 4, but JB having Coleman on a little bit of a short leash like Christmas and Fab their 1st years, with Christmas moving over to spell Coleman at center and Southerland coming in to join Fair in the frontcourt. Coleman would come in and play enough to average maybe 15-20 minutes a game, with Christmas averaging closer to 30 split between the 4 and the 5, and with Keita filling in at center as needed.
But I think your best defensive lineup problem won't work though, because having James play the 2 would kill us on offense since he doesn't have a great handle on the ball yet. (and besides, Triche is 6'4 and is a very solid defender already.) And I think having Keita and Rak on the floor at the same time would also kill us on offense. We'd need either Coleman on the floor with one of the two of them, or playing either Keita or Christmas with James and CJ also in the frontcourt.