A linebacker is a defensive player who lines up beside or behind the defensive linemen, depending on whether a 3-4 or a 4-3 defensive scheme is being run.
So that should be fairly straightforward, right? Well, as with most things in football, it gets more complicated when you look at the specifics. There are three linebacker positions:
Strong (Sam) linebacker- lines up across from the tight end. The label “strong” comes from the fact that the tight end always lines up on the quarterback’s strong side (right side if he’s right handed, and left if he’s left handed).
Weak (Willy) linebacker- he has more variation in his role because he’s lined up on the weak side. He can either cover the run or pass rush the quarterback.
Middle (Mike) linebacker – he’s the quarterback of the defense; he’s in charge of defending against the running back and the quarterback and also instructs the defense on how to align if there’s a change on offense.