Let's assume that stickman want's to drop the ball at frame 10. First we create the arm move. Select the ball and then select the "X" under "Animated Relation".
Continue moving the arm and you will see that the basket ball is not longer following the arm.
If you select the basket ball and choose matrix tool, you will notice two key frames that is added at frame 9 and frame 10. These are added automatically to prevent the basket ball from jumping.
Since the ball is released, we want it to fall down to the ground and bounce.
Click preview and watch stickman drop the ball.