Speaking around the release of his new book 'Relentless: 12 Rounds to Success', the promoter listed the best boxers of the past 40 to 50 years as: Muhammad Ali, Mike Tyson, Sugar Ray Leonard and Pernell Whitaker.
Asked if Mayweather wouldn't be an automatic pick, Hearn told us via Zoom: "I don't think so. Legends evolve over time. When you look at the weight divisions that Manny Pacquiao has won world championships in, you have to say Pacquiao should be on a list like that.
"But for me, I don't look at Floyd Mayweather as a historic fighter. One day we'll look back on Mayweather as a great, but he's got to be a little bit careful. To retire with dignity is a wonderful thing.
"To retire undefeated is amazing, but to do it with dignity and class is special. But he loves a pound note."
Hearn's implication is that the end of Mayweather's career, in which he's beaten up kickboxer Tenshin Nasukawa in a mismatched exhibition and got to 50-0 by stopping Conor McGregor in the Irishman's professional boxing debut, is in danger of tarnishing his legacy. Or at least it will if he continues down this path of bizarre crossover bouts.
But the Matchroom Boxing chief does admit honestly that if the rumoured McGregor vs Pacquiao showdown was offered to him, he would take a strong interest.
"It would be silly of me to lie and say we wouldn't get involved with that, because it's a huge commercial opportunity," he says.
"My problem with Pacquiao against McGregor is the same problem I had with McGregor against Mayweather. We're talking about two of the best pound-for-pound boxers ever in Pacquiao and Mayweather - and then we're talking about an MMA fighter who would struggle to win a British title.
"It's no disrespect to him; I think Conor McGregor is a legend of a man. He's one of the best MMA fighters of all time and one of the greatest self-promoters in combat sports. But it's a mismatch.
"When I did KSI against Logan Paul, for all the stick that I got, it was still a 50/50 fight between two blokes with very little experience. When I went to watch Mayweather against McGregor, I was in shock. There was a guy sitting next to me who looked like he was worth billions. He was so excited and after three rounds, he goes: 'Conor's gonna do it, he's winning!' And I'm looking around, and there's a lot of people thinking the same thing."
Hearn shares stories of the huge highs and lows of promoting boxing shows throughout his book, and is keen to give his view on the difference between a fight with mass appeal and one that boxing die-hards lap up.
"Sometimes when you talk about the casual audience and the hardcore audience... we almost mustn't get too close to the hardcore audience," he says. "They're very important to us. God bless them, they give me loads of stick, non-stop!
"But to grow the sport and build a fanbase and interest, we need to connect with the audience that might not watch Vasyl Lomachenko in the early hours of the morning, or might not even have heard of him.
"That's why when we look at pay-per-views, I've got a very good understanding of what lights the fire or ticks the boxes for a casual fan, and to give them value for money and entertainment as well. It's always the debate isn't it? 'Is that pay-per-view, is it not pay-per-view...' Well, the science is always in the numbers."
Expanding on his favourite all-time boxers, Hearn claims that the 'four kings' of the 1980s - the sub-heavyweight stars who carried the sport between the Ali and Tyson eras - mean a great deal to him.
"One of my heroes growing up was Sugar Ray Leonard," he says. "When you talk about Sugar Ray, Tommy Hearns, Marvin Hagler, Roberto Duran: that was really such a golden age.
"Then of course you have the emergence of Mike Tyson, but also great fighters like Whitaker and Meldrick Taylor. And obviously Chris Eubank, Nigel Benn...
"But then there's the fighters that might have tarnished their legacy, like Roy Jones Jr. He was an unbelievable fighter. But unfortunately he carried on for too long and I feel like he has damaged his legacy. Also James Toney, another one who's done the same.
"Time really brings out legends. Vasyl Lomachenko, Oleksandr Usyk; maybe Anthony Joshua and Tyson Fury in time - who knows? Canelo Alvarez, Floyd Mayweather Jr - perhaps in another 20 or 30 years' time, they'll be the ones that we talk about as some of the greatest ever. But for me, history doesn't always happen overnight."
Relentless: 12 Rounds to Success by Eddie Hearn is published on 29th October (Hodder & Stoughton, Hardback, £20)
Chosen for YouChosen for You
Most Read StoriesMost Read