A muff is the touching of a loose ball by a player in an unsuccessful attempt to secure possession.
Tag: loose ball
Rule 9, Section 7, Article 2
No player shall bat a loose ball other than a pass or fumble in flight, or a low scrimmage kick in flight which he is attempting to block in or behind the expanded neutral zone.
EXCEPTION: A K player may bat toward his own goal line a grounded scrimmage kick which is beyond the neutral zone and may also bat toward his own goal line a scrimmage kick in flight beyond the neutral zone, if no R player is in position to catch the ball.
Rule 8, Section 5, Article 1
Responsibility for forcing the ball from the field of play across a goal line is attributed to the player who carries, snaps, passes, fumbles or kicks the ball, unless a new force is applied to a grounded backward pass, kick or fumble.
a. The muffing or batting of a pass, kick or fumble in flight is not considered a new force; and
b. The accidental touching of a loose ball by a player who was blocked into the ball is ignored and does not constitute a new force.