You just don't go immediately from multiplication tables to algebraic inequalities. You've got to lay a foundation, slowly and methodically. Of course, there are the occasional prodigies out there, but don't count on it for your kid, or any of his teammates. Trust me, I know about his first hand. With apologies to Jack Welch, progress is our most important product.
Progress also needs to be measured realistically.
If not, he has not progressed appropriately. Remember, coaches can always improve technical shortcomings, but you WILL run out of time. Lay the technical foundation first, but systematically. As non-player coaches like me can attest first hand, most people don't have a clue how difficult it is to master the range of techniques to play the game well. But you can't teach 'em everything all at once.