I think it would be more logical to not attach the ball to your scaled player but instead position the ball at the location of the hand each frame using
positionentity ball,entityx(hand,true),entityy(hand,true),entityz(hand,true)
if the ball position is dependent on the orientation of the hand then child a pivot to the hand to get a correct reference point for positioning the ball
positionentity ball,entityx(hand,true),entityy(hand,true),entityz(hand,true)
if the ball position is dependent on the orientation of the hand then child a pivot to the hand to get a correct reference point for positioning the ball