You are losing a great deal of power by not cocking your wrists on your backswing and casting the club as your hands approach waist height on the down swing. When your arms are at shoulder height on the downswing, the club is parallel to your body, in my picture, when my arms are at shoulder height, the club head is still to the target side of my body. This helps to create lag for increased ball speed and distance. If I could figure out how to clip a still of your swing at that moment I would, but pause your down swing at the moment that your arms are at shoulder height and you can see the difference. If you look at Sergio's swing, the club head is still at about the same point mine is when his hands are halfway between shoulder height and waist height, he doesn't get the club head to the position you have it until his hands are at or just below his waist.
