#2 He isn't John Cena
Despite his immense talent in the ring and on the mic, one thing that did help CM Punk connect with the WWE Universe was his ability to portray himself as the anti-John Cena.
Throughout much of the 00's, fans were growing tired of John Cena's monopoly in WWE. He was Vince's 'chosen' poster boy for the company, meaning he was given far more opportunities at the title and quickly became the media franchise piece, hogging much of the spotlight from others. Fans' reactions to the guy are pretty mixed at best, however, as a lot of the so-called 'smarter' fans who appreciate in-ring work rate have tended to reject him.
Therefore, being put in a feud with John Cena is very much a double edged sword. You will receive support from 50% or more of the fanbase who are supposed to be booing you, but it's almost impossible for you to come out of the rivalry looking strong.There has been the odd exception to this, with guys like Brock Lesnar, Randy Orton and most notably CM Punk, whose time across the ring from John Cena actually helped turn them baby face officially.
In 2011 when Punk delivered his shoot promo, a lot of it was directed at the Cena/McMahon relationship and how many of the talents on the roster go unrecognised because of it. For so many in attendance, and watching around the world, this struck so much of a chord that people began flocking to Punk as their new 'John Cena alternative' in their droves.
Punk pretty much personifies everything that John Cena isn't. He has a long history of independent wrestling, doesn't have the typical physique that the WWE normally goes for, and isn't seen to be part of Vince McMahon's inner circle. Fans appreciate this, even if they don't totally buy into the CM character itself, and this has more than helped Punk become one of the most popular superstars in WWE history.