Our rotation at 4 and 5 did not make much sense last season after trading Olynyk and Fontecchio, and makes even less sense now. There is simply no place for Collins now: if he plays at the center (which is a bad fit anyway) and Kessler comes off the bench it will tank Kessler's confidence even more and seriously tank his value. If we play Collins at the PF he will be getting in the front of Hendricks who desperately needs development minutes. And if we move Collins to the bench his value will crater.
In short, one of them needs to go... and it almost certainly should be Collins, regardless of how hard it is to offload him.