THE WORD "defense" is psychologically poor, in that it implies that the team is defending itself against an attack. If some phrase could be invented which would denote that a team is not defending itself but is constantly striving to take the ball away from its opponent, it would more adequately express the proper mental attitude of a team not in possession of the ball.
Generally speaking, the theory of all defense against a running attack is to drive the runner toward center, as quickly as possible. In this way the attack is confined to a definite small territory. The salient principle of defense against the forward pass is for the line to force the passer to get rid of the ball quickly. This pressure disturbs the accuracy of the pass, and often so hurries it that the receivers have not sufficient time to get into their proper receiving positions. Against a kick, the line is again called upon to hurry the kicker on all occasions and to block the kick if possible; but to avoid committing themselves so thoroughly to these objectives that they will not be ready for any other kind of play which may transpire.
In the several methods of defense, there are again two schools, one of which believes that the men from tackle to tackle should stand squarely on their feet, but low enough to meet the charge of the offensive linesmen. At the snap of the ball they should advance against their opponents with their hands on their opponents' bodies. In this position they are ready to continue their advance, but should always diagnose the nature of the play before committing themselves to any one direction.
The other school believes that these same men should assume a crouching position, with both hands on the ground. When the ball is snapped these players should charge into the spaces between the opponents opposite them. In this way they are supposed to fill various chinks between the opponents, and also to carry them back into the offensive play. Against plunging types of plays this method is stronger than the other; but it has the great disadvantage of committing the players in a given direction, irrespective of the nature of the play, and is also further faulty because the players cannot see the impending play, nor diagnose it as quickly as if they were in the upright position and could use their hands to ward off their opponents.
Pitted against a close formation, the defense really need seven players on the line of scrimmage. To be sure, this arrangement leaves the backfield somewhat weak against forward passes, but on close analysis the offense can, by using certain of the backfield as buffers against the defensive ends, bring all of their linemen to bear on the remaining five defense. More often they bring five against three, and at the apex of a plunge there are apt to be three against one defensive player.
As has been stated it is the duty of the ends to hem in an impending sweep as quickly as possible. To accomplish this they cross the line of scrimmage on the snap of the ball and aim at the outside interferer in order to drive the runner in where the tackle can get at him. As the offense usually detail two interferers against the end, he must be careful not to get pinched between them, thus allowing the runner an outside course. The best method of preventing this is to use one hand on each of the interferers. In this way the end keeps free from the shock of the interferers' blow. He must also keep his feet, else the runner will certainly flank him. All told, this two against one battle is always worth watching.
MeanWhile the tackle is doing his best to come to the rescue of his hard-pressed end, but the offense before the ball is snapped are apt so to maneuvre an end, especially when a loose formation is used, as to be well on the outside of the tackle in question. Consequently unless the tackle is clever with hands and feet he will be "boxed" by this nimble end, who is re-inforced at the critical moment by more interference from the backfield.
The guards and center are usually outdistanced on a play of this nature but the secondary defense are sure to play an important role, in case both end and tackle are vanquished. Although he, too, is usually menaced by other offensive players he enjoys the great advantage of a roving position, thus making it difficult for the interference to locate him consistently and with precision. Furthermore, because of the direction of the play he meets both interferers and runner obliquely, at which angle it is easy for him to deal an effective blow. All told then, on plays of this nature he is in the great majority of cases the salvation of the defense and the thorn in the flesh of the offense.
On plunges and slants directed inside of tackle, there results a mighty conflict between opposing linemen. Of course the brunt of the battle comes on the two defense between whom the play is aimed. But players removed even two "holes" away can, by a vicious charge and a side lunge, often tackle the runner before he reaches the line. Conversely the offense must always lend lateral support even to plays of a plunging nature.
The cardinal principles of defensive line play in contending against a gruelling attack are to meet the offensive charge in a position strong enough to prevent being pushed back and at the same time to diagnose the play quickly and accurately enough to reach the "core" of the play, i.e., the runner. It is extremely difficult for the average spectator to see and understand the fine points of defensive line play, and it would be equally difficult to describe them in words. Suffice it to state that good line play is of vital importance and that, granted a parity in all other essential factors, a very slight superiority in this one department is sufficient to bring victory in the great majority of cases.
When opposed to an open or kick formation, the defensive line are still called upon to meet a close-running attack minus one player who has assumed a position ten yards back. From this position he threatens sweeps so seriously that both ends and tackles are compelled to move outwardly. Furthermore, the backfield needs assistance to cope with a probable kick or forward pass, so the center often goes to their aid, thus leaving the spaces between the various linemen much wider than when lined up against a close formation. Hence each lineman has to cover more ground laterally than against a close formation. In 1914, during the game against Yale, the Harvard team, with a kicker in position for a drop kick, executed seven consecutive plays, all of which were directed at points which were successively exposed by different members of the Yale team in their anxiety to prevent the drop kick which was never played.