What is wrong with his character exactly?
Half the time, he's a boring smiley jokey Cena copy, the other half he's a violent psychopath and bully. Both halves are portrayed as a wonderful, stand up guy.
If they could simply allow him to be an anti-hero who is not exactly a role model, but is badass and targets the bad guys, he would be one of the best in the company. He doesn't even need to go heel, just a harder kind of face, because the Cena-lite stuff doesn't suit him at all, it didn't suit Punk and it doesn't suit Sheamus. When he first turned face, he was still a rough, tough, violent brute, he just aimed it at the heels (like being brave enough to go toe to toe with Mark Henry during his Hall of Pain run). He got much better reactions and was much more entertaining then (he'd kind of run his course as a heel, prior).
He's become one of the most consistently good wrestlers on the roster, and I expect by the time he retires he'll be seen as one of their best ever big man wrestlers. I just hate how his character is. It's not entertaining.
They're beginning to move him in a better direction in this feud with Big Shoe, however.