Alexander Povetkin was the standout heavyweight of the era outside of the Klitschko's, and a lot of people thought that a 209lb Huck beat him. I don't think that Huck was even the best cruiserweigth of that era. If you take away the Klitschko's, then the super heavyweights of that era, don't not look so super.
Size obviously matters, but not to that extent that some people make it out to be. I mean Klitsckos aren't winning only because they are big. Sure it helps but they do have a way more powerful will then someone like Chris Arreola. Like the last era atleast before AJ / Fury came long was not that good. Heavyweights where slow, somewhat overweight and not really in fighting shape.
Boxing is primarily a skill and cardio sport, but size counts (inversely proportionally) as you go up the ranks, reflected in the increasing weight ranges for each larger weight category. But the bigger the body, the bigger the heart wants to be. And this is a bigger issue than being "strong", because sadly, the bigger the heart doesnt mean better cardio - the bigger the heart is, the more crippling a limitation it is, because it doesnt pump as efficiently.
Only those young and inexperienced jump right to a heavyweights size. So many more variables to consider before one ever discusses height and weight.
Floyd weighed in a few pounds under what he could've today. Here is his statement on it. https://streamable.com/1fhkj
This whole argument's a complete strawman. No one ever, at any time, stated that a fighter under 200 would automatically lose to a fighter over 200 regardless of the minuteness of the weight differential, so the futility of even addressing that idiotic point is evident. Seems no one in the classic section whose affinities rest with the black and white brigade can fathom the idea that weight actually plays a huge part in the modern HW division, because the best big fighters themselves have comparable skill and athleticism to the fighters of old. It's fixated in their minds that because Dempsey, Baer et al, happened to knock over some oafs that they would have no problem knocking over genuine top quality heavies of the modern era. It is in fact the nostalgia freaks who continually obsess over size, only in their case it's the reverse: that no matter how big, strong and athletic a fighter might get he won't ever be a match for their 180lb heroes. Because, ya know, Willard etc. The size matters argument is actually absurdly easy to fathom: that so long as all else remains even, the bigger fighter will have a better chance to win. That's why it's ludicrous to imagine Dempsey or Marciano ever beating Lewis or Wlad.
I actually think today's fighters are on average a bit smaller than the mid 90s lot, at least at the top of the division. Taking away Joshua the only other legit SHW is Ortiz, and he's not appreciably bigger than a lot of fighters of the past like Bruno, Witherspoon or Mercer. Parker should be around 230 max, Wilder consistently fights in the 220s, as does Povetkin, and Pulev shouldn't even be in the top ten by current run of form. Prior to that you had fighters like Jennings (220s), Adamek (210s), Ibragimov (220s), Chagaev (220s theoretically), Haye (210s), Cunningham (200s) and Chambers (200s), all top level fighters who competed successfully in the division. The majority of guys above 240 at the moment are there because they're fat.
But all rarely is equal when you compare the best big heavyweights to the best small heavyweights. The best small heavyweights are generally much better in terms of speed, work rate, and most crucially technique. Sometimes necessity became the mother of invention for the smaller heavyweights.