Shifts

[ajmc]

You might consider that the defense, observing all sorts of activity on the part of the offense from the point of breaking the huddle, understands that at some point the entire offense must pause simultaneously, for that 1 second, before someone can go in motion and the play will begin.

In essence, all the shifting and movement before that 1 second pause is deceptive and meaningless, as to when the play will commence, and that pause is designed to provide the defense with an opportunity to identify and react to the "final" offensive set.