I do not understand this nonsense of 'whether the batsman is backing up too far.' Why should he back up at all? His bat must be grounded behind the line. The line belongs to the umpire as in the case of checking a no-ball, or a run out, or a stumping. Why give this benefit of 'backing up' at all? Do away with it. Ground your bat behind the line till the ball leaves the bowler's hand. Simple.
I do not understand this nonsense of 'whether the batsman is backing up too far.' Why should he back up at all? His bat must be grounded behind the line. The line belongs to the umpire as in the case of checking a no-ball, or a run out, or a stumping. Why give this benefit of 'backing up' at all? Do away with it. Ground your bat behind the line till the ball leaves the bowler's hand. Simple.