Re: A request for air squat help
He's being too mobile with his low back, I think he gets too much extension in the low back then lets it all go loose to get into the bottom and rounds. Overall his upper body and neck are loose.
Have you taught him how to keep his core/torso tight with air in the gut?
I wonder if he would be a little more balance if you had him goblet squat.
I'm usually a big fan of butt back as far as you can, but you might have him try to have the knee bend soon after the butt comes back. I wonder if he is getting too much weight behind him and loses his balance.