The similarities both of these fighters had in some of their biggest fights strike me as strange, mostly because of how they're almost identical. Fitz was outweighed by Jeffries almost exactly forty pounds both times he fought Jim. The weight difference between Bob Foster and Ali? Almost exactly 40 pounds. The only person to ever cut Ali, as far as I know, is Foster. He outjabbed Ali and marked his face up pretty badly. It's well known that Fitz deformed Jeffries face to the point where it was literally hard to identify him afterwards. Credence to the fact that it's more than possible to affect even the most durable heavies of all time even with a massive weight discrepenacy?
I guess the key diferenc is that Fitzsimmons had more sucess at heavyweight. Cant quite put my finger on exactly why heavyweights had so much trouble getting Fitz out of there but I think his durability must at least have been respectable.