He was putting a new schwamus valve in his car and the stelner linkage broke, smacking him right in the arm. This caused a partial infarction of his bi, tri and quadcept muscles. Very lucky here as a total infarction would have been season ending. He didn't start wearing the sling until just before finals started, not because he needed to, but he thought it might net some sympathy points from a few teachers not to mention the CDI (chicks dig it) factor. The infarction is healing up nicely and he'll be good for spring ball. I don't know all this for sure but I think this might be what happened.