I think I have two major disappointments outside of the ones already said, Danielson's release is up there but these are the main two I would put out:
Firstly, Rey Mysterio.
Since last year, he's been on a downward spiral, but since the turn of the year, I have heavily lost a lot of respect for him as a superstar. While I have no doubt over his skills and being involved in some of the best matches, the person himself is one I truly despise. In the space of 7 months, he has been in three World Title Matches, screwed over CM Punk, annoyed me personally at a Smackdown taping, injured the Undertaker and won the World Title. This just adds to things of why he seems like such a political problem in the Smackdown locker room, a show which is usually full of the selfless members of the locker. But all I've seen this year is Rey winning matches he doesn't deserve, getting big calls that he somehow bitched his way into, and becoming a liability around other superstars, affecting them via injury or screwing their momentum by other means ala Punk and Ziggler.
This is the guy who currently stands as World Champion because of Undertaker being injured...didn't Vince forget that Mysterio actually injured him in the first place? Simply put, Rey Mysterio this year and thoroughly proven why he is such a dislikeable superstar who is only liked for merchandising, he can't even hold a candle to John Cena, while I may not be the biggest Cena that is.