Well BJ has always had terrible cardio by most standards. For a 155lb fighter he should be able to go much longer. There is a reason he used to be called "the best first round fighter in the world" early in his career. He wouldn't need sean sherk like cardio, but his stamina was among the worst in the division, or in welterweight for that matter. If he had the cardio to hang for the second and or third rounds I think he would have beaten Nick based on the first round and the way he was slipping punches and had Nick stepping back after he got tagged.