No idea what BJ's injury is, but I do know that concussion can easily occur without any direct blow to the head. Concussion is basically a mild to severe bruising (which is really a hemorrhaging) of brain tissue. Any kind of whiplash motion that causes the brain to rattle around in the skull's braincase can cause it.
If it is concussion, it seems a little premature to bring him back for the UT game. Once you've had a concussion, it's much easier to suffer subsequent ones, and without proper healing, the effects are cumulative. Mild to moderate concussions usually require three weeks or four months of healing, depending on the severity. Healing time also differs by the individual.
Bottom line is, if Catalon's injury was a concussion, best not to rush him too quickly back into the lineup.