In a rubber match, I really call it a tossup. In my mind that fight will come down to 2 elements.
1. BJ's cardio. If he works on that, he has a MAJOR shot because he's a much more skilled and technical fighter, not to mention his scary flexibility and explosiveness.
2. Mentality. If Hughes takes him lightly because he just beat him, that will be his downfall. If Penn comes into the fight intimidated of Hughes because he stopped Penn for the first time in his career, that will be PENN'S downfall.
Any fight involving these 2 guys is way too close to call because the second you count anyone out, they prove you wrong. No one thought Penn would win the first fight, just like practically no one thought Hughes would win this one. These guys are so close to each other in skill, the fights between them will always come down to the slimmest of all margins.