Ight, in my mind passing the guard and taking the back are BJJ terms thus I apply BJJ guidelines for using them. Typically 3 seconds is the rule for how long someone has to maintain position to get points, Penn had both hooks in for less than a second and it was the same thing with all of Sanchez's pass attempts. Neither would've been given points for passing the guard or taking the back, so I think it's more than fair to say that Diaz's guard has never been passed in MMA.
Rogan's a commentator, his job is to hype fans up while calling the action. How many times has he confidently proclaimed, "that's a wrap, son" when a submission wasn't even close? It's the same thing here, Rogan will say someone has passed the guard before he has secured position. It's not a knock on him, that's just the nature of his job. He also said he thought Riggs needed a finish in the 3rd round against Diaz to win the fight, doesn't mean anything.