Fury clearly did take it seriously. He was in the best shape he's been in years.
There is a bit to unpack in this sentence and imo it tells the really important part of the story.
"
He was in the best shape he's been in years."
I agree. (And I think we are largely on the same page here)
But, to be in "the best shape he's been in years." ... is partially hinged on Fury having been out of shape at times.
Fury was fat and out of shape vs Ngannou and he notoriously blew up to 400 pounds after the first time he won the belt.
Usyk has never gotten fat or badly out of shape that I am aware of.
There is an ENORMOUS difference between the conditioning you attain when
A) you are already in very good shape and then you add a few months of rigorous training on top of it.
vs
B) the shape you get in when you go from fat and out of shape to visibly looking reasonably fit (and let's be real Fury has never even gotten to the point of looking lean and jacked/cut).
The biggest difference I personally noticed was recovery time. When i have done A, besides having much more endurance before getting tired, you also recover almost immediately and you can push on even in a "anaerobic" state.
Aka, you are gassed and you can still go.
For boxing/combat sports this also heavily influences recovery from being rocked.
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Additionally, and worthy of note:
Usyk, being already/always maintaining a high baseline fitness level, is devoting the vast majority of his camp to technique, timing, fine tuning.
Fury on the other hand has to devote a significant portion of his time and effort to fitness. There is only so much "bandwidth"
Wait, so Fury didn't take Usyk seriously now?
Not seriously enough. See above.
Sounds like he needs to DM David Goggins for that conditioning
I don't think that would be enough.
He needs Dr Emmett Brown and his DeLorean.
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Usyk is the better boxer, better athlete.
The only thing that makes it even debatable for Tyson to have a chance to win is his enormous size advantage, which I don't think he really uses all that well in most of his fights.
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TL/DR - I have my doubts as to whether it is even possible for Fury to close the gap in fitness to a sufficient degree to have a great chance to win. With his size you would think he may have a punchers chance regardless but Tyson isn't the biggest puncher and Usyk is very defensively responsible.