There is no doubt that Greb had a grade A chin, but what we can also say is, he could be hit hard enough to be dissuaded a bit. Gibbons did that very thing will some crisp hard blows that beat Harry up and slowed him down some. You can't take some of the shots Fitz would dish out to the head and body and not be dissuaded some. Still though, Greb could win a decision and do enough, but it could go either way in my book.
Fitz is one of the most under rated near forgotten ex champs ... in his day he was universally recognized as the fighter of his age .. I was watching a fight of a prime Bob Foster last week was took note as the announcer said (at the time) old timers considered Foster in style and power to Fitzsimmons. Anyone with that power and body punching ability should be taken very seriously. AS great as Greb was he had serious trouble with Norfolk and Tunney and Ftz matches up well with him.
https://trove.nla.gov.au/newspaper/article/135310403?searchTerm=rosenbloom o'brien&searchLimits= Returning to the comparison i made of their top 10 opponnents, particularly O Brien vs Rosenbloom. The above article is interesting in that it lists Philadelphia Jack O briens take on Rosenbloom. he rates Rosenbloom higher than himself and other champions from his time. It might have been more promotional than anything else but it is still interesting.
Taking the names out of this one for a moment. If you have a shorter skilled swarmer who can't punch hard vs. a taller skilled puncher who can, each with hand speed who wins? There you have it. Robert beats Harry.
Fitz used "illegal handwraps" against Jefferies. He might try the same trick against Greb. The tape he used was 1900's "gas pipe" repair tape.....kinda like today's "Duck Tape".
I made a joke about Fitsimmons before, but in all seriousness this is an excellent fight. I like Greb, I liken him to Joe Calzhage on steroids with the hardest of chins. Fitsimmons would have a puncher's chance against litterally anyone in history. But here I like Greb's constant pressure and out-of-the-rules bullying. I'd pick Greb by decision. He's just to aggressive and has a (imo) good enough chin to take Fitsimmons on. The style match up favours Greb imo. My own question would Fitsimmons be Greb's best win?
At "LtHvy", Greb busted up Tunney in one, was very competitive in 2 fights, and lost one to Gene that he admitted to. At MW....a victory over Fitz, is better than his win over Walker.