The defensive has two jobs, one to tackle the person that is running and sack the quarterback if it is a passing play. Defensive linemen are the first stopping point of the defense. If two people sack the quarterback both tacklers get a 1/2 a sack. Some teams have three men on the line, some have four. Speed and strength is very important to a defensive end because he must be able to fight off blocks. He must also be able to spin quickly away from the tackle's block or use his speed to go around him.