Also, it's easier to teach the knowledge, etc, side than it is to acquire
high amounts of athleticism. So much of being able to jump high, etc, is innate. The body, even with all of today's advanced lifting and training and eating is less pliable than the mind. Can't change your height for example and while I had good jumping ability, there are some guys who could mostly lay in bed for 6 months while I trained everyday and they would still jump higher than me, I'm sure.