If a big man need only jump high enough to force a 9.4" diameter basketball through an 18" hoop 10' off the ground. The laws of physics would indicate that the farther away a ball is when it is released, the more difficult it is to make the basket. DH and Shaq have better FG %'s because they dunked more. Kareem played at a time when anyone wanting to dunk had a price to pay from the enforcer on the other team. His body wasn't made for high impact collisions and he knew it. He lengthened his career greatly by using the skyhook.