Being a WWE Superstar requires three major skill sets, and not having any one of them kind of disqualifies a wrestler from the claim. These three skills are thus:
1. In-ring ability - Not only do you have to have impressive moves, you have to be able to several in a row, and they have to look crisp and clean. Whilst looking both natural and at the same time it is very tough to do.
2. Mic skills - are the way the wrestler connects with the crowd. He has to be able to communicate his role, while still sounding normal. You have to be able to speak your lines and at the same time not sounding forced.
3. In-ring chemistry - This is the ability to function with your "opponent" and make the match look believable. A meathead like Ryback who can't pull his punches believably looks so fake and boring to watch. A wrestler who won't sell injury in a match can't overcome the odds also.
Let's look at some examples before we discuss CM Punk.
Hulk Hogan was good at 2 and 3. He could communicate with the fans and sell, but (in America, at least), he kept his skill-set limited. His matches were always the same. Others who fell into this category would be the Rock, and John Cena.
Bret Hart had very good in-ring ability and good in ring chemistry, but he was only passable on the mic. Certainly not the best there is, the best there was, and the best there ever will be. Others like him would be Daniel Bryan, Owen Hart, and Samoa Joe.
Edge had a pretty good skill set, and clearly had mic skills, but his chemistry was always lacking. His limited ability to tell a story in the ring seemed to be the reason he often won by sneak attacks. Others who seemed stilted in chemistry would include Booker T, Jack Swagger, and Christian Cage.
Now think of guys who had all three: Ric Flair, Shawn Michaels, and Steve Austin, were are major long-term champions who were very successful.
So we should ask ourselves, does Punk have a good skill set? Absolutely! He is great in all kinds of wrestling: he can fight, he can fly, he can grapple, and he has submission moves.
Does Punk have mic skills? Does this need an answer? Punk is the greatest talker of this generation. He doesn't have to scream like Flair, he doesn't have to use endless catchphrases, and he doesn't have to pepper his talk with expletives.
So how about his chemistry? Well, Vince seems to trust him to wrestle just about anyone in the company, and he had the longest reign as world champion since Hulk Hogan's first run twenty-five years ago. I've never heard anyone complain that Punk won't sell. So, that doesn't look bad either.
So, at the very least, Punk is definitely in the conversation of the greatest in the world. To reach the levels of Flair and Steve Austin, I think he has more work to do, but there is nothing holding him back. Since Steve Austin and Ric Flair aren't really doing much anymore.