This. Povetkin has a larger arsenal of punches, better head movement, better workrate, comparable power. Mercer would be a tough guy as always but I don't see him as having nearly enough guns to deal with Sasha.
Prime-for-Prime, Best-for-Best, it's Mercer W UD 12 (with him pulling off a late stoppage win being a good value-for-money bet). Despite a relatively successful career, during one of the most stagnant of Heavyweight eras, Povetkin did not beat anyone on Mercer's level.
Povetkin was a guy who would actually turn it up enough to win close rounds in tough fights. Mercer tended to settle into a “silent agreement” or slack off and hope that his power would bail him out in tough fights.