LOS ANGELES -- There are many different defensive fronts the Trojans offense faces throughout the season, but there few that consistently see on a weekly basis. With a lot of last season’s success in the air coming from what the offense was able to do on the ground, we take a look now at what the front seven sees from week to week.
The 4-3 defense is the most commonly used defense on every level of football. It starts with the nose tackle, who will line up shading to the left or right of the center depending on the strength of the offense. The defensive tackle will always line up on the outside shade of the guard and his alignment on either the left or right guard is based on which side the strength of the offense is called. If there isn’t a stunt or blitz called, then the nose would be responsible for the A-gap that he is shaded too in between the center and guard and the tackle would be responsible for the B-gap that he is lined up in. The defensive ends are lined up in a tight or wide 9-technique over the tackle or tight end. Their jobs are to contain the edges of the line of scrimmage against the run while racing up to try and sack the quarterback in passing situations.
With the zone blocking scheme that USC runs, going up against a 4-3 defense allows for bigger plays in the run game. The zone scheme allows offensive lineman to not focus on a particular man but rather an area. With the zone, usually one lineman will be working with another lineman to his left or right and the two will block whoever is in their assigned area. On the backside of wide zone running plays, the backside tackle or guard is assigned to cut the man on his inside. With the four big bodied players on the line of scrimmage who want to penetrate up field to stop the running back or quarterback in the backfield, their eagerness to rush up field makes it easier for the backside to be cut, leading to bigger gains as a result.
The 3-4 defense is becoming more and more popular throughout football. In this front the nose tackle is lined head up over the center rather than in a shade and two defensive tackles are lined head up over the offensive tackles as well. The job of the defensive linemen in this formation is not so much to penetrate up field but rather to disrupt the blocking of the offensive line by playing through them and playing the gap to the left and right of either the center or tackle. With that being said, in the 3-4 front every gap on the line is the responsibility of the defensive linemen. With this concept, it gives the green light for the four linebackers to run around the field and be more aggressive.
This defense it makes it more difficult for the offensive line to get a good push at the line of scrimmage. With the center and the two tackles’ defenders heads up on them playing the two gap, it makes it very difficult to get leverage with the zone. Another wrinkle that the formation takes away from the zone blocking offense is the ability to not be able to cut on the backside. With the D-linemen responsible for both gaps instead of one, they’re slower off the ball, thus not creating enough momentum for the offensive line to cut them on the ground. A lot of offenses tend to run the ball outside and away from the middle of the defense, but sometimes the best way to gain yards on the ground against the 3-4 is to attack it by running power, traps, and sometimes draws up the middle.
The bear front is more of a pre -nap adjustment or a secondary front that teams will complement the 3-4 or 4-3 with. In a pre-snap adjustment, the defensive end on either the strong or weak side will steam down to a 3-technique before the ball is snapped. The shaded nose tackle will line head up on the center, and either the SAM or WILL linebacker will line up on the line of scrimmage taking the place of the defensive end that steamed down to the 3-technique.
The bear front is used more to stop the run and to try and eliminate any double teams by the offensive line. If need be, most offenses can handle the adjustment of the different blocking assignments before the snap of the ball, but because there are now eight defenders in the box, it leaves at least one one-on-one matchup on the outside. If the quarterback can recognize this early enough and change the play, then he can call a play to get a first down, if not more.