 If the quarterback drops or loses the football at any other time, it is considered a fumble, as if any other player had dropped it.It is referred to as the tuck rule because the ball leaving the quarterback's hands is considered a forward pass even if the quarterback intends not to pass the ball, but instead continues the forward motion to tuck the ball back into his body.Only once the forward motion of the arm is completed, and the ball tucked into the quarterback's body, would a subsequent loss of possession be considered a fumble.