When you're considered the greatest welterweight of all time - not just in the UFC, but in all of mixed martial arts - just what is left to prove? There are those who would argue that his final, split decision win over Johny Hendricks means he should fight him again, but the fact is, he won that five round fight based on the same judging rules that exist today (the 10 point must system), and Hendricks hasn't done anything of note lately besides badly missing weight, falling ill, and being pulled from his last fight. He beat champions and ex-champions and every major title contender in the division. He avenged the only two losses on his record, definitively. What does GSP have left to prove? Nothing.