QUICK ANSWER
A muff happens when a player touches a loose ball but never gains possession of it. You will see it most on punts, when a returner drops the ball and either team can recover it.
A muff is when a player touches a loose ball but never gains possession of it. You will see it most often on punts, when a returner drops the ball and either team can recover it.
A dropped forward pass is not a muff. It is simply an incomplete pass.
Where You Will See A Muff
Punt Returns
This is the most common example. If a ball bounces off a punt returner as he tries to catch it, the ball is live and either team can recover it.
If the kicking team recovers, it gets the ball. A swing like that can change a game, which is why returners are coached to let a difficult punt go.
Kick Returns
A returner can also muff a kickoff. This is often less costly because he usually has more time to pick up the ball.
Muff Vs Fumble
The difference is whether the player ever had possession.
A fumble means he had the ball and lost it. A muff means he never had control of it. For example, if a receiver catches a pass, establishes possession, and then loses the ball, that is a fumble.
A muff recovered by the other team can swing a game much like an interception, because the ball changes hands.
Can A Muffed Punt Be Returned?
Under NFL and college rules, the kicking team can recover a muffed punt and keep the ball, but it cannot advance the ball on that play. Rules can differ at other levels of football.