Hot Stove for Aroldis Chapman's Pitching mechanics

well, one thing he point out is that

after followthrough , Chapman can not stand still, good point

but

when he say that when the front foot is stand still, the hand still behind the head, is that really a matter?

because a lot of pitchers have this ~~and i do not see any problem with that why he mention that for Chapman?

well, what do you think about it?

Its about staying on top, he is really fast to foot strike and his elbow isn’t up in time to stay on top and throw downhill. Instead, he has a tendency to rush and get under the ball (elbow drops) when you do this its very hard to throw down.