Any more comments on this.
AFAIK, we are taught to move parallel to the base line. So,
a) walking the runner back to 3rd means moving parallel and perpendicular to the foul line; as opposed to 45 degree angle or forward toward the base line.
b) walking the runner back to 2nd, only if runner at 3rd not moving forward, also parallel to the base line; as opposed to 45 degree angle or forward toward the base line.