The main stat to me is the quality of competition. As of now, Usman has only beaten 1 current or former champion in Tyrone Woodley. GSP has 2 wins over Hughes, 2 wins of Penn, and 1 each over Serra, Sherk, Hendricks, Bisping and Condit albeit he was interim. That is 9 wins over former world champs. Throw in a solid wins over Jake Shields, Nick Diaz, Prime Josh Koscheck 2x and Jon Fitch and the comparison isn't really even close.