What it is

The flexbone is a formation with a fullback behind the quarterback and two slotbacks standing a step behind the line, just outside the tackles. The tight end and wide receivers spread the field.

In a game

It is the basis of the triple-option offense. The quarterback chooses between giving the ball to the fullback, keeping it, or pitching to a slotback, depending on how one defender reacts.

More detail

Several service academies run versions of it, because it lets a smaller team with disciplined blocking beat bigger opponents. Defenses struggle because each player has a specific task, and a single mistake gives up a big gain.

Animated diagram

1. A fullback stands behind the quarterback, and two slotbacks stand a step behind the line, just outside the tackles.
2. The quarterback can give the ball to the fullback, keep it, or pitch it to a slotback.
3. He decides by watching one defender. If the defender takes the fullback, he runs wide with the pitch.