Originally Posted by
IndividualThoughtPatterns
By starting lower (not extra low or whatever- just low enough that your shoulders are directly over the bar) you more efficientlly initiate the pull with your legs, making the bar coming of the floor towards you (instead of straight up) while shifting the weight towards rearfoot. It also prevents the bar from going away from you after explosion (presumebly the USA lifter's problem).
And by the way: ''Understand that hip height is a product of our two basic position criteria (bar over the balls of the feet and arms vertical from side), not a criterion itself.'' From the link posted above.