Returning your left shoulder at impact to its address position does two things: First, it gives you clean contact, allowing you to trap the ball between the turf and the clubface. Second, it stops you from “hanging back” on your right side, or doing what I call the “sway and stay.” Swaying and staying is a high-handicap move that produces slices and hooks in equal amounts.
Here’s a helpful hint for the all-important Step 3. Picture a knife pointed at the outside of your left shoulder at address. Don’t overdo the move to the point where the Knife plunges deep into your shoulder — just do it enough to feel a little puncture. In other words, cut your shoulder, not the ball.