i have run with him 5 or 6 times in 5 mans, and he does ok.  he tends to pull more agro than some mages, but overall i think he understands his class.  i think it is simply a case of maybe him not being the most out going, but when asked to join a group or if someone he feels comfortable with starts one, he asks to get into it.  i would suggest reaching out a littel more to him.