Bodypunching yes your right, defense is a bigger advantage for Napoles, Armstrong is ofcourse better in close quarters too
............Napoles had a great right uppercut that he'd throw off the hook or jab (he seemed to rarely throw a standard straight right). That uppercut would play heavily here. I see this as an ugly fight, and not as full of extended exchanges as one might think, as Napoles liked to work from a little bit of a distance. Not long range by any means, but there was a zone just barely within punching range where he seemed real comfortable. Amstrong would try to take that away, but I think in a clinch-filled wrestling match, Napoles just edges him.
Fans who missed the 70's may criticise me for this, but I believe that Napoles was the creme of the crop of welters, and a master fighter all around, a uniquely gifted fighter...he would be too much for even the great Armstrong, and would deck and punish Henry en route to a decision or even a late rounds tko. Mantequilla was the best at welterweight, with his only possible flaw being his tendency to cut and swell around the eyes.