There is a lot of study and memorization involved in playing at the top level (or even the amateur level). Once they lose the will and/or ability to keep up wi

There is a lot of study and memorization involved in playing at the top level (or even the amateur level). Once they lose the will and/or ability to keep up with others, then they'll start declining. In my experience, I see most kids peak around their senior year in high school, where college and other responsibilities start to dominate their time.