Robots have been build which can knock the large ball off the barrier while quickly traveling under the barrier. It could be said that the robot is in both the middle zone AND the goal zone while dislodging the large ball. When the large ball is moved, I have seen it fall outside of the field.
Where should the large ball be placed/returned? Does it matter if the robot is moving from goal zone TO middle zone vs. middle zone TO goal zone? Or should the referee try to determine if the robot was in both zones at the time the ball leaves the field?