Are you only picking up these biomechanic books or are you actually reading them? If you are reading them, then it is a sad day for the field of human kinetics when you graduate. You are only book smart without any street sense. Yes, you can use those terms in your argument but your application of it is all wrong. You could only be right if you are referencing a flat footed serve that beginners tend to do. Maybe you serve that way. I don't know.
I agree. I don't see people leaving the ground on their heels or the balls of their feet. The last thing touching the ground ARE your toes. Maybe JV serves with his tibialis anterior, extensor hallicus longus and the peroneus tertius muscles flexed causing his feet and toes to point upward?