You must realize that people around here know about boxing and are not the casual fan like you are. If you knew about Ray Mercer you'd know he was a fearsome knockout artist before he met Holmes. He was as- if not more- dangerous than any Povetkin. Holmes schooled him 4 years after the Tyson loss. The guy who had just annihilated unbeaten Lennox Lewis couldn't even score a knock down against an even older Holmes. If you think Povetkin could just do what Tyson did - N0. Nobody just does what Tyson did. That post was a joke.
There's not much between them. Mercer has the better wins and faced much better opposition so the edge has to go to Mercer.
Mercer was extremely inconsistent, lets not forget his struggles with journeymen, and Damiani was absolutely schooling him before the late Mercer rally. Other than that Holmes was no longer capable of beating top fighters.
Damiani was much , much better than Tackam , who Povetkin was trailing on the cards against by a wide margin.