Roy Jones Jr vs Prime Mike Tyson you know because skill is more important than size.

he did things more beautiful than mike

 

Roy was more talented than skilled. Mike was both skilled and talented but undersized.

 

Well if size was the end all as your suggesting Jones shouldn't have been able to bounce J.Ruiz around the ring the way he did. Fat James Toney fighting 40-50 lbs above his best fighting weight Shouldn't have been in the fights against Peter's, Oquendo and Rahman. Yet all those fights were close.
Those are some recent examples of well schooled fighters taken it too natural heavyweights. Of course Jones would get crushed by Tyson. But it wouldn't be the size that crushed him, it would be the combination of skills and size that would be the difference. And yes Better skilled smaller heavyweights from earlier eras would crush these lumbering novices carrying World Titles today.

 

Jones was a reflex fighter once those reflexes went so did his greatness. His lack of fundamentals and a good chin let him down.
Tyso had mad technical skills but a abandoned alot of them as his career wore on.
Tyson is by far the better technical skilled of the two IMO