This is a basic structural test. It helps you test the hip position for pressure control plus the basic bows of the body if you have awareness of that training.
You can test if you hip and knee position is good for power control and force flow feedback.
If you drop the ball the you do not have the stance position control for contact with your opponent and your stance is not active. So make sure you feel the neutral / Active and Issue positions.
This is not the full structure, it is only the starting point.
Thank you