I think Hopkins would smother Greb and frustrate him, great style against the windmiller who seemed to use a ton of physicality and volume to overwhelm opponents. Hopkins also carried his talents to LHW well. Greb would be a lot smaller and would struggle with the bullying tactics of the larger and incredibly savvy Hopkins.
Off in "yeah see, c'mon see" Humphrey Bogart land, maybe. edit: but seriously he had never seen a Hopkins, I guarantee it, I don't see a parallel from that age with the technical mastery of a Hopkins nor the size at that division.
Tunney would be a better test for Hopkins. I think a relatively average punching and small for the time middleweight would not be able to roughhouse a guy like Hopkins. Robinson, Burley, Basilio, Fullmer, Winky Wright, Toney, Hagler, Monzon, even similarly sized Griffith would probably give him hell. The level of boxing increased a lot between 1926 and 1956 I think a lot of tough customers exist around 160 and it's hard for me to rate Greb as fully dominating any of those names above.
I think that he would be a difficult assignment for anybody, because he could either outbox or outwork almost anybody. The men who had the most success, were generally the ones who took the fight to him, because giving him room was fatal.
I doubt Hopkins was much more skilled than Tommy Gibbons or Mike Gibbons tbh, Hopkins hasn't done anything Greb hasn't seen before
He rough housed heavyweight Tommy Gibbons, Gene Tunney, Battling Levinsky, Billy Miske Tommy Loughren, Tiger Flowers, Mickey Walker and Maxie Rosenbloom. I could go on,,,,,he'd rough house Hopkins.
I guess I just feel otherwise. I think a guy like Randy Turpin could probably beat Greb down for example. Robinson would massacre him, and Hopkins was the size of ranked heavyweights of the day and has as deep a skillset as anyone. To say it would be some walk in the park for a half blind 5'7" welterweight to crush Bernard Hopkins is more hyperbolic than the inverse imo
If Robinson struggled with a poor man's Greb in LaMotta then I certainly don't see him doing well against Greb. Greb wasn't a small middleweight himself and regularly gave beatings to the world's best 175-200 lb fighters. Also you forget mentioning that Greb did have his eyesight in both eyes until 1921-22, including his peak year 1919.
I believe Hagler would have a far easier time against Greb, than he would against, Jones Jr. M. Nunn, and J. Toney. Hagler feasted on better fighters that were aggressive brawlers. ( As far as we know, because theirs no real film on Greb, and the writers opnions that so many hold as the absolute truth, were probably long dead before Hagler was even born.) Monzon Robinson Jones Jr. McCallum And quite a few other very good-great middleweights over the last 60-70 yrs....
If we could only see him we could determine who matches up well...but as it is we need a fighter with an engine and tough as nails....MMH had the engine but so did Vito Antuofermo....when you look at Gene Tunney a man who has his number it seems Freddie Steele, SRR, Monzon, Nunn and BHop has the style to do the same if they could deal with a buzzsaw like him....his description reminds me of Calzaghe with a meaner spirit.
Greb never had a Ray Robinson to lose 5 times to, so calling him a poor man's LaMotta, especially having seen no footage is hard for me to accept. LaMotta is not a bad comp for how I see Greb doing in the 40s-50s. Struggling is a harsh word for Robinson considering he went 5-1 in the series where the most memorable fight is nicknamed a "massacre" on his opponent. He was caught a bit vs. LaMotta, but LaMotta paid a price that nobody else could have conceivably taken during that time period during those fights.