The spine tilts toward the ball at address, and when the player swings back, that tilt moves to the right. So to keep the spine over the ball, which is the goal, the player has to tilt to the left during the backswing. The first move going back is this tilting action. It causes the shoulders and hips to turn on a steep downward angle, the right leg straightening and the left knee flexing forward.
As the left shoulder turns down, pointing almost to the ball, the hands move on a circular arc around the body, not up and away, and the arms stay on the rib cage. When the left arm reaches parallel to the ground, it should be angled 40 degrees inside the stance line. To golfers who've been told to swing back along the target line, this will feel way too far inside.
What It Feels Like
The hips are level at address, but because the spine tilts toward the target going back, the right hip turns much higher than the left. It should feel as if the right hip is moving up and behind the body.