there is a lot of BS in boxing do not belief the hypes this my advices lots of rumor & ' grand ' claim & all evidences points to opposite
Well there are examples of fighters losing five pounds a day for five days, consecutively in fight week. This, as you've said, is not impossible. What has changed, dramatically, is that fighters can do this and then performs as world-class fighters. It is not the weight-loss - it is the science of replenishing the fighter post weight-loss. Fighters can do this to themselves, then get into the ring with a notable size-advantage and no downside. This was not possible on shorter-lead weigh ins and it is not remotely something HWs did. Joe Frazier could unquestionably do this and unquestionably make 175 by doing it. Fighters do it to weigh in at 154, 155lbs. It's all about % of bodyweight lost. If Joe trains down throughout he's looking to shift about 15lbs by the time he gets to cut for 175lbs. It would be very easy. This is not controversial.
You don't think Frazier had a massive size advantage over Foster (even after Foster put on weight to meet Frazier)?
Well officially it was 19 pounds. Granted their were rumors the scales were off for Frazier's weigh in and his true weight was 204-206 but either way, it was a significant weight advantage. Frazier would just about have to kill himself to get down to LHW imo. I feel he'd be much better at cruiserweight.
Every single era we've seen a former CW step up and have success. Spinks, Holyfield, Haye, Usyk have all been ranked either 1 or 2 in the world. I'm never again writing a HW off as being too small. Even the current champ, Fury, was dropped by Cunningham. Never again will I write someone off based on size alone.