Q: If the release is always up, and if the release is always full out, HOW (mechanically) do you change the arc for shorter or longer shots in order to control distance? The concept seems very sound, but we don't seem to understand how you can vary the arc if you're always releasing the ball up and the extension is always full out. Help!
A: If your power and distance are exactly the same for two shots, then you would not vary the height (or arc). But if, for the same distance, you generate additional leg power (jump quicker, feel stronger, just decide to jump more strongly), then you will have to shoot higher or you will be long.
It's an instinctive thing. You will know to shoot higher if you have extra energy and lower if you do not.
You aim upward at different angles to give you that variation in arc, not always "up" at the same angle. The goal is to develop a "constant" Release motion, "full out" (about 70-75% of max), but because distance and power are usually varying, you have to change arc to compensate. I think most shooters try to have the same arc and vary the power in their arms, wrist, hand and fingers. That is very difficult to do, especially under pressure.
The free throw can be managed by practice to be about the same UpForce (leg drive) every time, plus the same, practiced Release, so the arc will be about the same. But if you are fatigued and feel less power as you go to shoot, you can lower the arc. If you are excited or nervous and feel extra energy, you can raise the arc. Varying arc is how you control distance! It will all be instinctive, not something you create a formula for.