This is false. Dynamite was drawing over 1 million viewers before Punk and Danielson even got there. They were doing that with their core wrestlers such as Jericho, Omega, Moxley, Hangman, Young Bucks, Lucha Brothers, Cody, MJF, Darby, Sammy etc. Also, selling out all their ppvs. They drew based on their collective brand of wrestling.
Punk popped a rating based off of a nostalgia moment. Once the moment came and went people lost interest because his matches sucked. The only match that was even memorable was the dog collar match with MJF and that was mainly because of MJF. If you want to hold the attention of this fanbase you got to deliver in the ring.