Weight Shift
Weight transfer is inherent in all athletic throwing and hitting movements. It creates some initial momentum, which is quickly turned into angular momentum (rotation), it enables you to push into the ground to leverage the big muscles in your legs, and it and stretches out the big muscles in the left side of your core. All of these things are necessary in order to generate maximum club head speed.
**Some small lateral movement of your lower body is desirable at the start of the downswing to facilitate a proper weight shift, but your head must stay centred in order to keep the bottom of your swing arc consistent, and thus strike the ball cleanly and consistently. Good ball-striking becomes increasingly difficult if your head moves off the ball.