Yes, because he does everything better than Valuev and has far more punching power despite the fact that Valuev is much bigger. I'm not saying that fighters from the past are worse than today but fighters like Muhammad Ali and Sonny Liston should be compared to cruiserweights and not to modern athletic super heavyweights.
So skills can negate physical advantages? Just to be clear, that's what you're arguing in the specific case of Joshua vs Valuev?
Of course they can but not in this case and not in the case that Muhammad Ali would win against AJ. Valuev is not an athletic guy, his extreme size is a disadvantage for him, he had not even great punching power and he was a champion despite the fact that he was only an average boxer, so his size worked for him to a certain degree but he couldn't compete at elite level.
Valuev was better than he got credit. he was a distance fighter, and was durable. And he never did lost badly. For a massive guy with two bad knees, he did alright for himself. I think Joshua beats him, but Valuev generally did well with bug guys. He couldn't handle movement, which Joshua doesn't really present.
So the principle has been accepted, good. Maybe then, when people argue in favour of Joshua vs Ali, Tyson etc the '6'5'', 240llbs argument will cohabit with an assessment of skill too. No one argues Ali is the same size as Joshua, they argue his skill-set would be enough to negate the physical disadvantages. There's a case to be made for this, although it's a tough ask to make it stick. I actually do agree Ali would struggle with skillful super heavyweights from the Lewis era onward. But that's based on more than simply size. That said, from things I've read, you do seem to take a wider, smarter view of era vs era match-ups. Some don't. #gravity
Apparently, Valuev didn't want to be a boxer, he wanted to be a poet but because of his unusual size was forced to fight. And yeah I agree, he gets discredited because of how he looked rather than how he fought...
valuevs physical disadvantages in cardio will be key here, they are bigger than joshuas physical disadvantages.
A guy like Dominic Breazeale for example would lose to Muhammad Ali, because his size couldn't negate the huge difference in skill level between him and Muhammad Ali. Size is not all that matters but it is a huge factor when both fighters are on elite level and Anthony Joshua is clearly an elite level super heavyweight, nothing to take away from Muhammad Ali, i'm a big fan and he was a great fighter in his era and he would probably rule the cruiserweight division today but in a matchup between him and Anthony Joshua, i would put Anthony Joshua as the favorite.