Cena hasn't had a great year, and yes he played a part in the two Show PPV matches being ass. Hell, it was his crappy selling that made the JD match suck, and Cena is usually a great seller. And yes I thought the Edge match was also shit and that wasn't ALL Edge's fault. However, he has had good matches this year. The 30 minute match with HBK from Jan was decent, and that was mostly because of Cena. He had two very good TV matches with Show. The Smackdown one was a real PPV quality match between them. He had the short match with Swagger where he still was able to make Swagger look great and elevate him. His part in the Elimination Chamber was short but sweet. Hell, I even thought the JBL match was decent. It was a typical "match is secondary to the angle" deal but they still did well with it. The tag with Chavo against Miz and Show, again was also pretty fun.
When it comes down to it, Cena is a very good wrestler who flaws are obvious, like his goofyness and his now (almost surprising) selling inconsistancys. I also think Cena is someone who has been restricted by the PG pillow fight setting of the WWE. If he had been able to be more wreckless and violent in something like the Edge match it would have been a whole lot better. Cena is great in a big, violent brawl, but can't do them really in the current WWE.
Meanwhile, when was the last time Triple H had even a decent match? Even on TV, his matches are not good. I think he became really exposed last year with the way he was constantly in title matches and yet produced practically nothing. Triple H may have been the only wrestler to singlehandedly stink up a Wrestlemania main event.