Slender i think you are mostly correct. Except: a select few 190 lbers who were the best ever would beat all but the best 240ish lb. guys. though admittedly some 2nd tier guys like a Mercer might beat them too. And Douglas was 231 vs. Tyson. though your general point is understood.
Yes, a hall-of-fame little guy beats a so-so big guy, but Buster Douglas beat MIKE TYSON. BTW I think Patterson was probably the best HVYT of the 1960s outside of Ali and Liston, better than, Quarry, Foley, Ellis, etc.