Another fight where the challenger ran over the champ was Couture/Sylvia. That was the epitome of "being outclassed".
Also, Cain wasn't himself in that first fight. It's like something Rashad Evans said, before he got run over by Machida. He said that once he got the belt, he became afraid. When you're chasing the guy with the belt, you're one of the wolves, but once you have the belt, you realize that all of the wolves are after you. He said he had nightmares and dreams about losing, and it all came together to become the Rashad Face. I think that Evans/Machida 2 would also be a lot different from the first fight, but I'd say that it would be much closer, and no guaranteed win for either guy.