Did Mayweather sparred and beat someone like Tyson in sparring? Did Mayweather beat someone like Toney or Spinks? I don't think so. Well if Dempsey who saw Robinson,Ali and many others said that Greb is the fastest man I think that is enough to know how fast he is. Maywaether never beat some LHW let alone top 3 LHW.
Greb was only a good fighter by early 20th Century standards. Boxing has evolved A LOT since he fought. Really, the ONLY reason Greb is held in such high regard is because there's no footage of him, so we just have to take people's word on how good he was. So many fighters from before the days of cameras have essentially become tall tale heroes.
Neither did Greb. There is just the story of him getting the better of Dempsey in some sparring rounds, and the fact that he beat Tunney. But that's it, and the size disparity wasn't that big, it's like Mayweather beating a middleweight. Your examples are kinda far fetched since Greb also wouldn't stand a chance against Tyson or Spinks. No it's not enough, not by any means. That's just Dempsey's opinion, and he could very much be wrong. But even if he's right, that still don't make Greb faster than some of the men Mayweather faced. Greb was a MW, Tunney was a LHW, there's just 1 weight class between them. Mayweather would only need to beat a MW once in 5 attempts in order to replicate what Greb did vs Tunney. Also, Tunney is candidate for top 3 LHW based on what he achieved in his own era, but not based on skill. He'd get his arse handed to him bigtime by the likes of Charles, Moore, Spinks, Foster, RJJ.
1) Greb fought at higher weights than 160. He seems to me to be more likely to be closer to a natural 168 than 160 2) Mayweather never fought at 160. Indeed, even 154 was probably well above his optimal weight. Floyd is at a serious size disadvantage here 3) It's not just "a middleweight" we are talking about. It's possibly the #1 middleweight in history. I could see Floyd beat "a middleweight" through sheer skill. But couple the size disadvantage to an opponent with real skill and Floyd knows his ceiling. For example PBF declined to meet GGG at 154, nevermind 160. 4) A guy like Conor gave Floyd all he could handle for four rounds with his size and pressure style. Granted that version of Floyd was past the sell by date but Conor isn't a real boxer. We're talking about a guy in Greb that's bigger, faster and renowned for his stamina, and most certainly a real boxer.
In this day and age hearsay just won't cut it. There needs to be SOME visual proof of all of this before we hold these old guys in such high regard. Especially when said fighters are universally ranked in the top 10 GOAT discussion.
Greb was beating HWs and LHWs in sparring and in actual matches which could Floyd only dream about. There is just story?Well everyone who witnessed that sparring claimed that he beat Dempsey. Did MayWeather ever had the balls to have a sparring with 40+ years old Tyson? Greb would have better chance against Spinks and Tyson than Mayweather. Dempsey and Johnson opinion.Also Tunney's opinion. If they claimed Greb is the fastest then I don't know how you can claim wrong. Greb was as fast as Calzaghe or even faster, perhaps he is better. Archie Moore himself said Tunney would beat him. Spinks and Moore would get destroyed by Dempsey. Also did Floyd ever dared challenging bigger man like,Canelo or Greb did? Also did Mayweather again fought someone bigger than him?
The size difference isn't THAT big. Yes, Greb was bigger than Floyd, but people as a whole were significantly smaller and shorter in Greb's time than they were in Floyd's time. Greb was all of 5'8. The average MW height today is 6'0.3. He would be a TINY MW by today's standards. And I'm not trashing Greb or anything. That's just a fact, backed up by TONS of evidence.
Greb: 168lb https://boxrec.com/wiki/index.php/Harry_Greb_vs._Gene_Tunney_(5th_meeting) I assume that pounds are still the same today as they were then?
Floyd reaches into the vault for a stack of cash to take into the past and says ‘Harry, just sit back and let me potshot you and I’ll hand you this, which is about 10,000 times your entire career earnings, and if you’re a good boy I’ll buy you some bling and teach you how to wear it.’ After losing a 20-round shutout decision, Harry is spotted with a gold tooth waltzing up and down the streets of Pittsburgh with a boatload of Santo gold around his neck.
Calzaghe had same style but was not as good puncher as Greb, wasn't as fast and did not had better defense than Greb.
He might be, but those 20 lbs he'd have on Floyd are meaningless given how much more skilled Floyd is compared to him. The no. 1 MW given his achievements in his era. If we had a time machine and brought him to the modern eras (say 70s onwards), he'd be an average bum. GGG is way better than Greb though. A real boxer, but with poor skillset compared to modern boxers. Of course Mayweather ain't beating Calzaghe, but Calzaghe is a million times better than Greb, he'd destroy Greb.