Yeah but CM Punk? I don't think he was an enough of a draw to bring in a lot of the huge WWE fan base. Get John Cena to fight in the UFC. That would draw and bring in millions via PPV and ticket sales. But how old is he these days, hopefully still young enough to fight someone good competitively.
WWE wrestlers may truthly practice some martial arts but it would be easy to adjust in real time or real action fights. Lesnar came from ufc but transition would be easy. But if cena would really go for money but i doubt that it would give his first game an impact wether he is a real fighter or not.