Imagine you're 5'8". Can you dunk? Yes, with tons of work and while you're young. But eventually you will turn 30 and not be that explosive and have good knees anymore. Then you can't dunk. What if you're 6'5" . Then, yes, with no work you can dunk and you can dunk forever. You turn 30, you turn 50 -- you can still dunk. This is why size, height are >>> skills, speed at the elite level.