A defender responsible for guarding receivers has many methods of preventing a catch. If the ball is thrown to the receiver they are defending against, the defender may try to bat the ball away, or somehow alter the course of the ball to prevent a catch. Each time a defender successfully deflects a pass, it is recorded a defensed pass. The total number in a series, quarter, game, or season is passes defensed.
This statistic is used by teams to evaluate how effective their defensive backs are at preventing a catch. There are many rules in the NFL that favor the receiver, so a defender must be careful not to interfere with the play while trying to defend the player. If a penalty is called on the defender, there is no pass defensed. If the defender is successful in deflecting the pass, he could create an opportunity for an interception.