Is his head swaying to much in the backstroke (and staying too much back on the downstroke) - or is it "perfect"? He's not following the ball with his eyes and swivelling head to any degree it seems..
His head is so far from center, it should have its own Zip Code.
I don't understand the Drill but I have a hard time finding value with it. I can imagine the problems it's causing but maybe someone else has used it to effectively learn something and I'm missing the point.