The OP put a question out there for you to answer. And it was not "Can Diaz beat GSP" it was "IF Diaz beats GSP..."
So either make that assumption or find a different thread to post in. Derailing threads (or at least attemting to do so) is not accepted around here.
Diaz beats GSP only if
you believe he can, I don't happen to fall into this category of people who believe he can and his name certainly shouldn't be tossed around anywhere near a super fight. Diaz is quite a few tiers below legit fighters (cream of the crop title holders) who are actually worthy to be included in a very rare category of MMA super fights.