The theory that the Hulk was on Sakaar for centuries instead of just a couple of years from Avengers: Age of Ultron to Thor: Ragnarok, is an interesting one and does seem to hold some weight if you really break it down. For one, the Hulk was finally able to speak. He didn’t have Banner’s intelligence, nor was he really able to articulate himself all that well, he was the brute that we all remember from the comics who could talk in broken sentences but still be understood well enough to converse with. Plus, the following that he’d gained on Sakaar seemed to argue for this as well since it would seem unlikely that so many of the citizens would be so zealous in cheering for him if he’d only been there for a short while. But unfortunately for this theory there are a few holes that, like the Devil’s Anus in the movie, just seem bound to tear the theory apart bit by bit. Here are just a couple.
The Hulk would be older, regardless of the time difference
While time on Sakaar moves differently from anywhere else it would seem the aging process of a body is still something that can’t be slowed down. If centuries had in fact passed then Hulk would have surely become a gray old man by that point, even if there was some sort of temporal effect keeping him from withering away. His healing factor, impressive as it is, can only do so much as has been seen in the comics, and despite the fact that it continues to heal him and possibly even halt the aging process a bit, the only thing that would keep him from aging would be the movie magic, as well as the fiction that Sakaar is in fact a place where time is a bit kooky and doesn’t conform to what we’re used to.
Fans are fickle no matter where you go and embrace champions quickly
Watch the WWE, watch any sport on TV, and you’ll see fans cheering one way or another based on who’s winning. You’ll see a large number of people holding to their favorites of course, but in an arena like this, with the only outcome being life or death quite often, the favorite is bound to be someone that’s left standing after two or three fights. Now if anyone has read or watched Planet Hulk, which is where Ragnarok got the idea for the arena fights, then they would know that the Hulk was being put through one fight after another on a continual basis. The fact that he’s the one standing after just a handful would be enough to rally people to his side, and this would only take a matter of months at best, not years and years. For those that might think true fandom only emerges after countless years of following someone it’s likely that they’ve never been to a WWE match, where people pick their favorites by the match, not by any sense of real loyalty. A champion is only the favorite so long as they’re winning in many cases, and on Sakaar, where winning means staying alive, this seems to indicate that the Hulk became the favorite very early on.
There are a few things that might suggest a greater passage of time, such as the fact that he doesn’t seem to fully recognize or care to see Thor at first. But given that the Hulk has always felt like the outsider of the group, and the fact that he and Thor have tussled in the past, it could have been that the thunder god’s arrival was more of an annoyance as his presence could have reminded Hulk of the times he was trying to forget and run away from. Then there’s the fact that he can speak in Ragnarok, albeit in a way that’s closer to the original manner that was used in the comics. If people remember, the Hulk has always been able to speak no matter that it’s not entirely intelligent and not exactly a stimulating conversation most times. But one needs to remember as well that the Hulk is also a constantly evolving creature as Banner and the Hulk tend to feed off of one another occasionally, meaning that certain skills and knowledge do get passed back and forth with their interactions. Communication between the two hasn’t always been a closed and unknown thing, as they have had to ‘talk’ to one another in the past.
So to be fair the theory does hold some weight, but not enough to hold up under the scrutiny of the many questions, pokes, and prods that can bring it crumbling down around the ears of the one that made it. It was a nice and very astute try though.