I understand why the Cavs kept Cunningham over Cooley. In their minds, there probably wasn't really a decision to be made, and I may have made the same call had I been in their position. But my guess is Cooley has more of a future in the NBA than Cunningham.
I guess there is still some chance that he figures things out, but he has been a professional for 3 years, after 3 years in college, and hasn't shown he can play his style of game efficiently in the NBA. After having traded for him, Dallas quickly gave up on him, and it has been downhill ever since. And he wasn't all that good at Oregon State either.
Big opportunity for him the next couple of months. Despite being a former first round pick, he has hardly even played in the NBA, and if he gets a few chances while Kyrie/Shump are out and acquits himself reasonably well, I guess it's possible the Cavs might actually keep him, and if not another team will give him a shot. Otherwise, it's back to the D League.