as for the question. Mayweather is so much better than Valuev, but Valuev would be too big and wear out Mayweather. I cannot even see this fight in my head really. The fact that you mention Valuev and ask could Mayweather beat him shows us how bad the heavyweights are now. That is why John Ruiz was champion a few years ago and Toney and Jones beat him. If they would have taken on Lewis, they would not have come close to winning.
"Could Pacquiao beat a Heavyweight if he's **** enough" = Stop posting, crazy ******* "Could Mayweather beat Valuev" = *Takes topic seriously* Oh, ESB.
No, even the blocked punches would still hurt through his guard and he's not gonna slip past every punch he throws. Not every single punch.
It's conceivable, yes. It's actually take a lighter, younger version of Floyd though, as opposed to the current one. He would just need to avoid punches all night and peck away. Valuev is as slow, plodding, and predictable as they come. A quick agile, small guy, could potentially grind out a win by being elusive.