Shallowing the club in the downswing is considered one of the magic moves. It keeps the face of the club passive, letting you develop more speed with your rotation without the need to perfectly time and manipulate the face. The result is consistency and distance.
One of the best drills for this is called the Under-Over Drill using the Tour Striker Educator. Start with the white Educator arm between your forearms at address. In your backswing, let the Educator arm work under your lead forearm and use your pivot and rotation to deliver the club and collect the ball. (Click for more on the Under-Over Drill)