I know we've had our bouts with each other THE PHILOSOPHER, but RJJ in his prime was a once in a lifetime fighter. Perhaps the single most dominant fighter I can think of (in any weight class) that has fought during my lifetime. More dominant than Tyson, more dominant than Lewis, or Holyfield or De la Hoya or Floyd or Calderon or whoever. Roy Jones Jr. didn't just beat opponents he toyed with them, he played with them. Could opponents have pressured him more, landed a lucky shot? Maybe, but we're talking 99 times out of 100 RJJ was as slick as teflon and faster than the speed of light or so it seemed.
Byrd at heavyweight may very well have troubled RJJ, Chris Byrd was a very good fighter, had quick hands of his own and a heck of a chin. But the issue is RJJ wasn't a real heavyweight, he never was so for him to jump up in weight and win a title (albeit a trinket like the WBA that Ruiz held) was quite a feat and honestly I think that should have marked the end of his career.
Michalczweski & Calzaghe weren't going to travel to the US to fight RJJ, neither was Ottke (though he's not mentioned).
McClellan got horribly injured before RJJ could fight him. Had G-Man not been injured who knows?
Steve Collins

Come on man! Steve Collins would have been thrashed by RJJ easily. Not because he wasn't a good fighter with great heart, but because he just didn't stack up to RJJ.
Julian Jackson had HUGE power dangerous to anyone, if he caught RJJ it might mean a KO....
IF. RJJ's speed and reflexes had a way of shutting up the big bombers of that time, look at the James Toney fight.
Eubank is the bargin bin version of RJJ.
Benn a dangerous dangerous man, but not all that difficult to hit. He was avoided by RJJ due to the result of the McClellan fight, not the stoppage win, but the brain damage. RJJ wouldn't have allowed Benn back into the fight the way G-Man did. When Roy decided he was "done playing" he'd finish you off right quick.
Jirov was a cruiserweight and RJJ had no reason to go up to fight him. I can tell you this much, Jirov was strong and tough but also slow and once again easy to hit.
Maske & Roccigainni were nobodies at the time, powder puff Europeans
Everyone else you listed is a reach. The guys who could trouble, maybe beat Roy Jones Jr. even in his prime are as follows: Bob Foster, Tommy Hearns, Gerald McClellan, Michael Spinks, Ezzard Charles, Archie Moore, and maybe some really old school guys like Tunney, Greb, etc but I doubt the older guys would have anything for Roy's speed & power. Roy Jones Jr is one of a kind, I am not sure we will ever see brilliance of that kind on display for as long as it was ever again.
Calzaghe beat a badly faded RJJ....had they fought Prime for Prime Joe wouldn't have been able to cope with the speed and power RJJ possessed, hell OLD Roy even knocked Calzaghe down in the first round.
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