I think a lot of this is Leon being smart enough to go where he'll actually play. Even if he was completely healthy right now, he'd likely be the 5th big on this team and be getting zero playing time. Even if someone went down, he'd still only see 10 mpg or best.
I think he went to Cleveland because when he's healthy, he'll be the 4th big and there's a good chance that Shaq and Big Z won't be healthy at some point, so he'll get even more PT.
It's a smart business move. Two years from now when he may have played himself into a new contract. That never would've happened here where he would have been completely buried on the bench.