What happen was, the week before the their bout, Punk announced he wasn't gonna re-up and he was basically going to take the belt hostage once he won at MITB,
The intro to the match was crazy cause it was in Chicago and they treated Cena like Public Enemy No. 1 and Punk as their favorite son.
He won, didn't show up at the following RAW, so Vince said that he was going to hold a 8 man tourney for the vacant title.
The next week Cena beat Mysterio in the finals of the tourney and Vince awarded him the title, as soon as he won the title Punk's new music hit and Punk was back.
Him and Cena had a face off where Cena tried to raise the title and get a pop, but Punk out popped him and Punk said that the real champ is here. They fought at the next pay per view to unify both WWE titles.
The storyline had so much potential, if they would of let Punk stay off camera with the title and show up to other promotions with the belt, they could of had him legit hold the belt hostage and defend it at Ring of Honor and shyt and people would of went crazy, it could of been a dope way to cross promote other organizations, especially since he was talking about taking it to ROH and NJPW.
Hope this helps breh.