Jeez, maybe I should tell you to shine something up, turn it sideways, etc. and get 500 thumbs up, too.
The Rock and John Cena are VERY similar.
Big muscled-up guys with expressive faces.
Both have truckloads of charisma.
Both known for their catchphrases and mic skills.
Neither are "wrestlers" -- punching & kicking is not wrestling.
Both have signature moves that are laughed at (People's Elbow & Five Knuckle Shuffle).
And both are derivatives of Hulk Hogan, the man who started that type of "superstar". I didn't say "copies" of Hogan; I said "derivatives" meaning Hogan was the prototype and Rock and Cena are cut from the cloth Hogan wove.
The Rock and Cena are so similar that to make comparisons and say one is "better" than the other would be like picking two apples from the same tree and claiming one is "better" than the other. The Rock is funnier, that we can say for certain. But he doesn't have more or better mic skills than Cena. The Rock, as does Cena, recycles and repeats his catchphrases over and over. But Cena actually does wrestling promos, while The Rock does insult comedy routines. Both are good at what they do in promos. They are equal in charisma. A lot of people don't understand what "charisma" means. In wrestling terms, charisma means to make large amounts of people CARE about what you do or say (booing or cheering means you care about what that wrestler does). It does NOT mean to make large amounts of people like you. The Undertaker's charisma trumps them both and he doesn't even need to speak.
Neither are very good at wrestling. Both are the generic punch & kick brawler you find all over the WWE roster. They punch and kick, do a couple of signature moves, do a finisher, then celebrate for 30 minutes as if they HAD just pulled off a 5-star Mitsuharu Misawa vs Kenta Kobashi classic. They are cheered (or booed) for their charisma NOT for their absent "wrestling" skills.
Cena is universally panned all over the internet as one of the worst wrestlers in the business, if not of all-time. Internet fans claim he has no mic-skills, no charisma, and they hate him. Their general opinion is "Cena sucks". If he's hated by so many people, and so many people claim he is untalented and boring, how can anybody POSSIBLY call him "overrated"? To be "overrated" people have to rate you highly, above what you SHOULD be rated. Cena is rated highly by only the most die-hard of Cena fans. Anybody who calls Cena "overrated" really doesn't understand what that word means.
Conversely, The Rock is pretty much regarded as one of the "greatest of all-time", especially now with all the bandwagon-jumpers hoping to see The Rock take Cena's place as the face of the WWE. These people are calling The Rock "the greatest". Which makes absolutely no sense because those same people call Cena "the worst". They are the same thing, people! The Rock is funnier, and insults everybody; otherwise The Rock's and Cena's "acts" are exactly the same. Generic punch & kick brawlers with truckloads of charisma, who got over because of catchphrases, "attitude", and massive pushes from Vince McMahon. When The Rock began in the WWF as Rocky Maivia, he was a very similar character to what Cena is today, and fans hated him. "Die Rocky Die!" was a common crowd chant. "Rocky sucks!!" was another.
If Cena is "the worst" and "sucks", then The Rock IS "overrated". Vastly "overrated". The Rock and John Cena are the same thing. You can't call one "great" and the other "the worst" with any degree of rationality.