Ali has a harder time with Frazier the 2nd time and with Spinks the 2nd time and Wlad has a harder time with Povetkin and possibly Peter. Still not so sure they would have lost though.
Sorry, but you're using a false equivalency to predict an alternative outcome here. For example - two cases - Wlad/Povetkin and Ali/Frazier II - are nowhere near comparable.
I'm comparing the tactics used. People like to point out how Wlad should have been disqualified against Povetkin, but you can argue the same for Ali in his rematch with Frazier.
Wlad's jab is probably the best ever in the division. Vitali's jab is very functional. Both of them constantly land first because they were 6'7 rangy and threw at a higher workrate that only the likes of Usyk, Ali, Marciano and Frazier could match despite their height and size. Vitali had the better chin and was much tougher but Wlad was a few levels above his brother in terms of technical ability I wasn't a fan of either but they both beat most heavyweights in history H2H Was the era bad? I thought so at the time but it could be how much they dominated it. The US era was bad but the post Soviet block fighters were a new introduction I suppose we have to imagine the era if they never existed, I imagine Lennox goes on a few more years, but let's set that aside and imagine the scene 2003 onwards without Lennox. You have Sanders, Ruiz, Byrd, Toney, Brewster, Danny Williams, Adamek, David Haye, Povetkin, Chagaev, Valuev, Eddie Chambers, Calvin Brock, Sam Peter, Rahman, Tony Thompson, Liakovich, Chisora. Probably some I've forgot. There would be some good fights if those men fought it out for titles and maybe the era gets remembered more fondly rather than both brothers routinely winning every round against opponents who weren't on their level. Bowe was heavily protected but look at his fights with Golota and Tubbs. He really struggled with a good quick jab. Holyfield schooled him with the jab when he actually got on his toes and boxed in the second fight. He hasn't faced a jab nearly as good as either brother. Look at Holyfield against Lewis, Moorer 1, Larry Holmes. He struggled with their jabs. Past prime Holyfield got outjabbed by Ruiz Both men have a chance of pressuring Wlad, getting inside and maybe knocking him out. But Wlad would be the most powerful puncher either of them faced alongside Lennox Lewis and Foreman. And the risk averse Wlad, no one managed to back him up until he faced Tyson Fury and Joshua, when his legs weren't quite the same.
Realistically? No, you can't argue the same. The difference between the two bouts is palpable upon watching them. Evoking the term "tactics" is useful here because it helps with distinguishing the two cases. One can suggest Ali applied the intermittent tactic of clinching, as part of a broader strategy. It was not sustained or persistent enough to be considered a substitute for boxing, or particularly excessive beyond what was typical. Wlad's fouls involved a variety of man-handling (holding, leaning, pushing, shoving, pulling and throwing Povetkin to the ground). The type, frequency, and preemptive nature of the fouling indicated it was a cornerstone of his strategy and a substitute for boxing.
Ali iniciated only a few more clinches than Wlad in that fight. And he was the only one doing so, while Povetkin was hugging Wlad for dear life as well sometimes.
It goes without saying that their respective CVs should be assessed individually but, apart from being brothers, they were business partners, management and promotional collaborators and a brand reflected in what is commonly referred to as 'The Klitschko Era'. In this sense, they were a collective.
Size has nothing to do with it. Lennox was too slick for that washed-up 2002 version of Tyson. He won all 8 RDs.