This was done similar to how they reached out to Alberto Del Rio, through an intermediary who is friends with Punk. The idea pitched was said to be a huge deal for Punk to be the top star of the company with pay similar to what Hulk Hogan was making. The idea is that Punk could be TNA's flagship star and if he signs now, he could help get a strong TV deal.
Punk reportedly expressed no interest in working in pro wrestling again.
CREDIT / SOURCE - Wrestling Observer Newsletter