The ref is supposed to hold the puck in both hands, in close to the
waist, and then drop it quickly without making any motion before.
Otherwise, players get jumpy.  I think it's just when the players are
already anxious and try to anticipate the puck drop that they jump the
gun.  Then the ref can throw them out of the face-off.  That's how I see
it, anyway.  Another thing I noticed while taking face-offs myself is
that the referee can be pretty picky about where you put your stick
beforehand.  It's supposed to be out of the dot, and if you put it inside
the dot in any way, the ref may throw you out if you don't move it to his
satisfaction.
 
-Brian Sprague
 
On Wed, 19 Oct 1994, Glen Keeney wrote:
 
>   Rule 6 Section 12 covers face-offs.  As a short answer, the "official
> shall order the individual(s) taking the face-off replaced for that face-off by
> any teammate(s) on the ice".  So much for the authority to make the change.
> Maybe your question was more about "sometimes they fake like they are going
> to drop the puck" and any such "faking" would draw the ire of several
> people so no official should be doing that.  Someplace I have read
> instructions for the correct procedure for an official to use, but on a
> quick perusal I couldn't find it in the rule book so must have heard
> it elsewhere.
>