RGA Student Swing Improvements
The arm plane at the top is something that varies from player to player, even on the tour. However, if the plane to too flat and the left arm is too low, like on the right, it can over-shorten the backswing and hurt with power. if it gets too high, it can be tough to drop the club on plane. Getting it just right (like on the left, in my opinion) can provide power and allow the club to drop into the slot.