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.
It took Junior a mere 64 seconds to figure him out the first time...
What has Cain ever shown that makes anyone think it'll be different this time around? When have you seen Junior taken down and kept down? Never in the UFC, when have you seen Cain dropped by punches? Twice, once of those coming against the man he'll be facing in his next fight.