I can't agree with the idea that nothing should lead anything else, that isn't how our bodies work.
But it is clear we aren't going to agree.
I will leave this with the simple point that the movement of the heaviest part of your body causes the rest of your body to move. This is a well established principle.
If your move your foot at the same time as your head you have to make a second movement to push your weight forward from your back foot. This is fine.
But when you get a surprise short ball you will not be able to move.
Mistake is an interesting choice of word, but given the topple method has been successfully coached for over 100 years I would suggest there must be something in it, despite your dislike for it.
"I can't agree with the idea that nothing should lead anything else, that isn't how our bodies work."
I've no idea where you get these nonsensical ideas. Clearly its not a science textbook of any sort. Normal people are perfectly capable of moving multiple body parts simultaneously, and there is nothing unusual or difficult about performing a lateral movement of centre of mass without leading with the head.
"the movement of the heaviest part of your body causes the rest of your body to move. This is a well established principle. "
The head isn't the heaviest part of your body though, this is just rampant nonsense. If your head is heavier than your leg, you have serious medical issues. and before you try to justify this nonsense with "oh well so and so said this", I can assure you I know that this myth is oft-repeated. Its still wrong.
"If your move your foot at the same time as your head you have to make a second movement to push your weight forward from your back foot."
No you don't. Again, I have no idea where you got this idea from. If you move your front leg/foot and upper body simultaneously, then your COM is also moving by definition. No second movement is necessary.
"But when you get a surprise short ball you will not be able to move. "
Why would you have moved at all before picking the length? We're talking about moving forward to address a full delivery, not pre-delivery movements. What on earth are you coaching? How is it possible that you're this confused about something so simple.
"the topple method has been successfully coached for over 100 years"
We thought the earth was flat for over 1000 years, it was still bullshit.
I would really recommend you put a moratorium on your coaching activities until you've taken the time to grasp some of the basic physical principles of biomechanics. If you're teaching this nonsense to students, you're doing them a serious disservice.