Under

Under is the defensive front variant of the 4-2-5 that shifts the line strength away from the standard even alignment, walking the Sam linebacker down toward the strong side while the nose tackle plugs the weak A gap. The NT and SUBLB tags tell you exactly what you are working with: a true nose over the center and a sub linebacker (usually a hybrid safety or slot corner body) filling the second linebacker spot instead of a traditional Mike/Will pairing. That personnel choice is the whole point of Big Nickel 4-2-5 Under. You keep four down linemen and legitimate run fits while fielding five secondary bodies, so you are not forced to burn a timeout or eat a personnel mismatch when the offense goes 11 personnel with a receiving tight end.