I'll agree that I thought the "rattled" part of Cena's promo was well done. The problem is that he pointed out the truth about the guy he's feuding with: Miz doesn't matter, Cena's gonna clobber him, and coast on to yet another PPV victory.
That doesn't make me want to order a PPV.
WWE is too protective of guys in that way. HHH never shows weakness or vulnerability, so I'm never interested in feuds he's in. Simply because the WWE's writing, production, and structure never give me ANY doubt as to what the outcome is. Same w/ Cena.
Now, you might say, "what about the Big Show feud that just ended? Cena showed weakness there!" And you'd be right. But Cena didn't show weakness of vulnerability, and seemingly couldn't be pinned, until he was hurled into a spotlight that burned/cut/electrocuted/killed Cena. It was so over the top it was absurd - thus enhancing just what we expect Cena to be willing to withstand.
Rambo was a good movie, but he would make a bad wrestler. Dig?
Still, Cena's promo showed some uniqueness and heart. Even if I find it ultimately meaningless.