Vision determines how quickly you get off the line of scrimmage after the snap. All that agility doesn't come into play until after he "sees" that the ball is snapped. 1-2 ticks are usually the difference between a sack and a hurry.
http://goallineblitz.com/game/player.pl?player_id=251068&playoffs=0 Season 9 was when I upped his vision from the soft cap, you tell me if it made a difference.