If the throw is designed to be thrown to a spot then he needs to keep his head forward and get close to that spot before he looks for the ball. It is like in baseball where they say to turn and run under the ball before you turn back and track it. It is hard to believe something simple like raining your glove or looking back too soon can slow you down, but it does. That being said, it is a lower percentage play that takes chemistry between the receiver and QB to accomplish. Hopefully, that is being developed as we speak.