When are pro tennis players in their prime? It seems like many of the successful pros make their mark by the time they are 20 years old. Does that mean that players who begin their college career post 20 years old are on plan B. By the time they leave college it wouldn't seem like they would have much time to make their mark as a pro.

For women, probably very early 20s, sometimes teens. For men, early-mid 20s.