Instead of having to unlock coach skills, how about distributing special skills based on points invested/milestones?
So for example anyone who has 90+ FH should earn topspin invasion or a choice of FH related skills.
Poison slices would be relegated to 90+ BH etc etc.
Monster defence would require heavy investment in speed and stamina etc.
At the moment people are building toons so that they can unlock certain skills which is counter productive. I know that currently you need certain levels in S&V for example to eventually earn drop shot artist etc but I think going this way, FLATTENS the skill gulf for everyone.