You’re right, it’s not a matter of logic, it’s a matter of necessity. Someone has to go whether it makes sense for them to or not. If it’s not Wagner, then it will be someone else, less voluntarily perhaps.
Watson is still a second tier bench player after his second year on the floor, and with the recruiting class coming in, his prospects for PT in the future look no better. Same with Davis. If Wagner stays, we’ll have him, Teske, Johns, Castleton and Livers as front court players. Not much of a prospect for Davis to be a factor there. As far as Brooks, I doubt very much whether he’ll be going anywhere after this season, but if DeJulius jumps him in the pecking order next year and he doesn’t find minutes at the two, he might think about it, while he still has two years to play somewhere else.