Does it have something to do with the arrow at full draw NOT being "level"? (v. the bow not being drawn)
Jeff, if your at full draw and aiming at a 20 yard target your arrow will not be level to earth, it will be point high/nock low. Your arrow does not leave the bow level when shooting at targets down range, remember the arch,
So if you draw a straight line from your nocking point, down your arrow that straight line would go straight over the target not intersect with it. (when at full draw).