Now you're changing the goalposts and adding variables. I didn't say that the 20 something was training as hard when he was a teen as the wunderkid. In fact most teen prodigys were already working as hard or harder than their adult peers when they ran their best times, e.g. Ryun, Webb, Elliott. They are not necessarily going to get any better. Others, who build up gradually in their early 20s and go on to run faster and achieve more are more talented than someone who takes everything from the well before they turn 21.