I am having trouble getting my 14 year old son to stop trying to crush the ball during match play. He often keeps his elbow in on contact and is not consistant. During drills when he is just using a fluid motion, it can be a thing of beauty. His easy swinging motion during practice has plenty of pace on it. When he plays points for some reason he will just start swinging wildly at times. I am trying different ways to create a new memory folder in his brain but its like pulling teeth. Any advice on breaking this habit would be appreciated.