One year ago, John Cena was progressing from a short feud with Edge to a new program with Triple H. During that time, his wrestling ability was beginning to open up (I don't want to say improved because his best matches were in 2003) and his gimmick became bearable. He was moved from being the #1 underdog, to being a viable competitor in the WWE. Move forward a few months and things were getting even better. We got the return of his belly-to-belly and top rope legdrop, two moves that were seemingly removed from his moveset throughout his first title reign. He stayed strong through the heat that he got against RVD and Hunter, and has finally found a wrestler who is more hated them him: Edge. His feud with Edge was absolutely phenomenal, imo. MAYBE it could have been cut short one PPV, but that didn't take away from the overall atmosphere. It put Cena back into a situation where he was chasing the title, which is always better than a face defending it. He was against a strong competitor who could still be beating. Things were interesting.
Fast forward through some inter-promotional stuff where he wasn't defending the belt except against K-Fed, and his feud (I use that term lightly) with Umaga, and you've got where we are today. John Cena is again being booked as the guy who is demolished at the beginning of a match and miraculously comes back at the end for the win. He's being shoved down our throats and pushed to the moon. And that worst part is, it isn't his fault. His wrestling is solid, his selling is great, and his move set is larger than most other wrestlers' on the roster. However, his gimmick is just sucky. The transition that they give him to be goofy one moment and serious the next just screams "I WISH I WAS THE ROCK!" to me. He can be funny. He can be serious. But he can't be both. It's the writers' job to realize this weakness and cover it up. Make him 2004ish goofy or make him mid2006ish serious. Pick one and stick with it.
So, in short, one year later, Cena's wrestling has improved, while his gimmick has gotten worse.