Playing defense in football requires many skills, but no position on the defensive side requires more well-rounded ability than linebacker. Defensive linemen have to rush the pass and stop the run. Defensive backs have to cover receivers and make tackles. Linebackers have to do both. They supply the signature to the defense with their ability to disrupt the offensive game plan.
Aggression and Defense
Make every tackle you can. Aggression must be a part of a linebacker's makeup and that has to come into play when you have an opportunity to make a tackle. You must throw off blockers who are attempting to stop you or get in your way. When you get your hands on a ball carrier, the key is to get low, wrap him up with both arms and bring him down.
Cover running backs and tight ends going out on pass patterns. Defensive backs will probably have their hands filled covering the opponent's wide receivers. However, running backs and tight ends have speed, athleticism and receiving skills. You have to be able to cover them without committing any penalties. Stay with receivers, knock passes down and make tackles to keep the pass catcher from gaining extra yardage.
Rush the quarterback on the blitz when that play is called. One of the keys to having a successful defense is being unpredictable. Defenses don't rush the same four defensive linemen every play. They will bring an extra linebacker or two on occasion to stop the opposing offense or force a turnover. A linebacker who can fulfill all his duties must know how to get low in order to get past the blocker and get to the quarterback.
Force fumbles from receivers or running backs who carry the ball loosely. A good linebacker has to sense the opponent's weaknesses and exploit them. Punish the ball carrier with hard hits and punch the ball out of his hands when you have the opportunity.