Just watched this promo.
John Cena is damn good at mic, and everyone knows it although not all will accept this fact. A fact, not an opinion.
John Cena's promo at recent Smackdown episode was very good and surely better than AJ's but mic skills have never been the latter's strength. That's why John Cena was quite better than AJ at delivering it.
Not to forget that AJ has improved at the mic too but not enough for Cena.