Being in great physical shape but doesn't make you an athlete. However, it does allow an athlete's inborn ability to be more fully expressed. It is very encouraging to see a talented baseball player working hard, doing what he has the ability to do in order to improve.
It's a rare person who can maximize his or her potential. Few people have the ability to dedicate themselves to anything 100%. I am certainly not one of those people myself. As an example, Kent Hrbek did very well for himself in his career but he also was an underachiever. Imagine what we might have seen if he had been the type of person who could do that. And this is not intended as a cheap shot at Hrbek because he, like me, is in the same category as the vast majority of people; he's just a familiar baseball example that came to mind.