Great read. I especially like the point of trying to move the weight forward without losing all 3 points on contact. Matt Boyd, in presentations, has added an interesting language twist which is not to ask someone to just move forward, but to stand and move a percentage of their body weight towards the ball of the foot. (You can here him describe it when listening to his presentation from this past National Academy on the First Chair podcast). When you add the thought of moving a percentage of weight in any direction and maintaining those points of contact it can create a powerful move with the ankle.