When has a Diaz fight ever been a letdown? Bisping is almost never in a lackluster fight. He alwasy brings it, whether he gets his ass kicked or he wins. Nick is gonna do his stupid antics but he will entertain for sure, whether it's at the thought of him out punching his opponent while high as a kite or getting his ass handed to him.
Both have notoriously bad attitudes and both are fun to watch whether they are beating someone up or getting smacked down.
I can't imagine it becoming a bad fight. I'd be perfectly happy with Diaz outboxing Bisping then him testing for Marijuana afterwards. Or him getting his butt scrubbed.