[BCGolf]

I believe it has to do with the weight of the golf ball. The ball weighs a little over an ounce and a half and the Clubhead weighs about six ounces. When taking a practice swing through the air many players allow the Clubhead to lightly brush the grass. When making the same swing through the golf ball the collision of the ball and lofted Clubhead forces the leading edge into the ground. The more loft on the Clubhead the further it is pushed into the ground creating a deeper divot.