During an appearance on The Joe Rogan Experience, The Undertaker revealed what he thought about CM Punk quitting WWE and then going on to join UFC.

"I didn’t understand it. He had an issue with the company. Sometimes people just wanna… they need a new challenge. But he was the top dude, he was a top guy for the company.

Sometimes, like I said, I don’t know enough because I wasn’t around enough at that time, but I don’t know that he had enough background [to fight in UFC]. It was kind of late in the game, I think, for him to make that transition."