Rotation Change is the difference in Rotation (the rotation of the putter face around the shaft) between the start of the stroke and impact with the ball, measured in degrees. Rotation Change (open) means the putter face was not rotated enough on the Forward Stroke to return to its original starting alignment. Rotation Change (closed) means the putter face rotated past its original starting alignment. Assuming the initial aim of the putter face is directly at the center of the target, Rotation Change of 0.0* is ideal.