He needs cardio, true, and I think he is best at 155. But the one thing people forget he needs most: gameplanning. He needs a coach/team that will not only help him build a gameplan, but help him train to actually follow it. BJ is one of my all-time favorite fighters, but he is an extremely stubborn and prideful guy, and so many times (both in wins and losses) he has passed up the easy victory. Basically, someone tags him on the chin, and he refuses to do anything but box from then on. His hands are amazing, but he needs to practice transitioning from strikes to TDs, using the cage offensively (rather than just to stop TDs), and generally winning rounds on points through timing and strategy.
Turn BJ into a gamer instead of a brawler, and I think he still, at this age, has a title within a year.