 Those three players are responsible for engaging the other team's offensive line, allowing the four linebackers to either rush the quarterback or drop back into coverage, depending on the situation.While the role of the defensive linemen is fairly consistent, the linebackers allow for the flexibility and versatility of the 3–4 scheme, and give defensive coaches nearly limitless options to confuse the other team's players and coaches.Depending on the situation, any number of linebackers can blitz, fake a blitz, "spy" the quarterback or running back, or cover receivers.