I'd like to think Cain is gonna put up a better fight this go round. That was a perfect hit to the temple in the first fight, it's gonna be hard to replicate that. If Cain dodges the first couple hits and gets in close, who knows what will happen with Cains devastating grappling.
As far as I remember, it was actually behind the ear, right there to mess up the equilibrium. But yes, it's going to be hard to replicate that punch. AND it's HW where one punch can easily turn the table. Before Dos Santos beat him, a lot of people thought that he'd reign the HW division for years. To count him out completely doesn't make sense.