Both The Rock and Brock Lesnar legitimately dislike John Cena or so WWE would have us believe.
The behind the scenes fallout from the match between John Cena vs. Brock Lesnar at Extreme Rules has been confusing to get my head around. First, Mike Johnson reported that Lesnar had a tantrum backstage thinking he had been double crossed by Cena when he didn't leave on a stretcher, instead opting to cut a strange promo to the fans where he claimed that his boss may be mad at him for saying this, but he's likely going home for awhile due to his battered arm. With the benefit of hindsight this interview was even more bizarre as Cena was back on Raw the next night with his arm in a sling setting up his Over The Limit main event with Raw and Smackdown General Manager John Laurinaitis. Then Dave Meltzer claimed that the tantrum was largely for show, to fool everyone into believing that Lesnar had quit the promotion before Raw, but he was still legitimately upset at things that had happened during his match with Cena. In particular, he was mad at a botched spot, one that almost caused him to blow out his knee, where he tumbled over the top rope when executing a springboard clothesline on Cena, which he blamed on his opponent pulling down that rope on purpose.
The latest twist to this completely perplexing story comes from the latest Wrestling Observer Newsletter where Meltzer asserts that Cena went into business for himself, as that promo was to the best of his knowledge never scripted by the WWE creative team ahead of time:
In addition, when [Lesnar] was given the finish, he was told he was being protected because he was destroying Cena, that Cena would get the win, collapse, and have to be helped out of the ring and left for dead. Instead, Cena did a weird promo that based on what we were told, he was not authorized to do. Everyone backstage, including Vince McMahon either had no idea what he was doing (and it was not in the script for the show), or maybe Vince knew and was pretending. But given how it turned out, I'd bet on the former.
Personally I'm highly sceptical that consummate company man Cena would ever make such an egregious deviation from a planned finish to a major pay-per-view. Either he colluded with Vince to get one over on the high maintenance Lesnar, or much more likely in my opinion Lesnar knew what Cena and Vince had planned all along, but it was kept secret from almost everyone else in the company, so he had a plausible reason to be pissed off at both of them and feign a possible walkout on WWE.
Some of Meltzer's sources blamed both participants having their bells rung during their simulated fight together for the peculiar antics that went on afterwards:
Others have said both Cena and Lesnar were knocked silly from stiffing each other in the match, and Cena's weird promo may have been because he was on auto pilot by that point in time from all the shots to the head during the match.
I suppose that's possible, but could equally be a fake excuse to give Cena plausible deniability that he didn't intentionally sabotage Lesnar or people grasping at straws because they don't want to admit to themselves that they got played by three conmen.
As a statistician in my day job, I'm a proponent of Occam's razor, which is the principle that "all other things being equal, a simpler explanation is better than a more complex one". Thus, I favour the basic hypothesis that as the interview was on television then it must have been approved a priori by both Brock Lesnar and Vince McMahon, and all stories to the contrary stem from WWE's growing obsession at going to extraordinary lengths to get online buzz from reality based, worked shoot storylines.