turning the hips from the top really fast is not always the fix. If your weight does not go down into your feet but you just turn your hips, you will tranfer no energy or resistance. if no energy/resistance is transferred from the feet up then there will be no solid left side and no left shoulder snapping back up and in, but rather spinning out and roundhousing. Stand up and twist your hips 25* to the right and left and notice the shouders react very little, now do the same but shift your weight down into your lead foot and the shouders will react more.