PG ...the difference in starting tall and starting wide can be linear stride momentum that is used to uncoil the hips. I think when this player feels he cannot fire his hips, he is ABSENT the stride momentum he was using when he started tall .
Watching Glaus one would think keeping the head still before toe touch could be a bad goal.
Watch his stride and head move until toe touch and then his perfect rotation around his secondary stance
http://www.youthbaseballcoaching.com/mpg/Glauss02.mpeg