As long as Cena's around, Punk isn't going to be "that guy." Cena is the undisputed #1 top guy in the company, and CM Punk is a distant second. Think back to when all of this started. Punk won the strap from Del Rio at Survivor Series, but The Rock's in-ring return, and his shaky partnership with John Cena was the main focus of that show. As Rock VS Cena at Wrestlemania drew closer, Punk was pushed further into the background. Cena and Kane's "Rise Above Hate" feud became the number one priority in WWE, and after Elimination Chamber, WWE kicked into high gear with building Rock VS Cena. Jericho and Punk delivered a pair of great matches, but the storyline side of their feud was very underwhelming.
After Mania, it wasn't unrealistic to expect more spotlight for CM Punk. The Once In A Lifetime match was over, Rock was preparing to take another hiatus, and Cena had to gather himself after losing the biggest match of his career.....and then Brock Lesnar shows up. Lesnar/Cena became the dominant storyline, and they main evented a pay per view in Punk's hometown. After Extreme Rules, Lesnar breaks Triple H's arm, and a very lengthy build for Lesnar VS HHH at Summerslam started up shortly after. Again, Punk had to take backseat to a more prominent storyline, because Triple H VS Lesnar was the bigger deal.
Of course, along the way Punk had an outstanding feud with Daniel Bryan, and they delivered some fantastic matches together. But in the grand scheme of things, AJ's emergence as "the crazy chick" slowly overshadowed Bryan and Punk's feud for the WWE Championship.
Raw 1,000 rolls around, and Punk turns heel by attacking The Rock, starting his crusade for respect. He bullied Jerry Lawler for a while, but the fans didn't begin to fully accept him as a heel until Paul Heyman came into the picture. Punk escaped the triple threat at Summerslam, and as expected, Cena and Punk delivered another five star quality match at Night Of Champions. Also, during this time, Cena's drought without winning any world titles became a strong focal point of the major storylines, and Cena did win the Raw briefcase in the main event of the MITB pay per view.
So far, Punk has survived the threat of Ryback, and I have no doubts he'll go into the Rumble as WWE Champion to face The Rock. But when Rock starts to appear on TV again, the spotlight is going to shift towards him again. And rightfully so, because The Rock is the bigger draw.
CM Punk's year long reign has been fun to watch. He's been an entertaining face and heel champion, but he's not the guy. There's nothing wrong with that, because as others have mentioned, other wrestling stars from the past held the world title, but they routinely took a backseat to Hulk Hogan. Still, that doesn't diminish their work as champion, and the same thing can be said about Punk. In today's WWE, having a year long title reign with the branded championship is something to admire, especially when you consider WWE's hot potato treatment of their world titles these days.