Two safeties, two deep halves, one seam

Cover two shell, a american football defence drawn in Playmaker: 11 of our players on the pitch. — Left defensive end — 1 of 11

American football · Defence · 11 of your players

A cover two shell hands each safety exactly half of a fifty-three yard field, which is about the most a safety can genuinely cover. The seam between the two of them is the rent it pays.

Open in Playmaker

Opens on a american football pitch with the shape already drawn. Free, no signup.

Where the eleven defenders stand

Four down linemen sit a yard on the defensive side of the line of scrimmage: two tackles about five yards apart over the guards, two ends outside the tackles. Three linebackers are six yards off the ball and eight and a half yards from each other, which covers the middle of the field between the hashes and not much more than that.

Both cornerbacks are wide, five yards in from their own sidelines and three yards off the line, turned to face the receivers rather than the field. And the two safeties are the formation's name: fifteen yards deep, twenty-three yards apart, one over each half of the field.

Splitting the deep half is the entire idea

Each safety owns half of a fifty-three yard field and nothing else. Half a field is a distance a safety can actually cover, which is why very little gets over the top of this coverage outside: the corner squats on the flat, forces the receiver one way, and a safety is already standing where the deep ball would land.

What it gives away is the middle. Two safeties splitting the field means neither of them owns the space between them, and the seam — up the hash, fifteen to twenty-two yards deep, behind the linebackers and in front of nobody — is where a tight end or an inside slot lives. Every offensive coordinator in the sport knows it. The bet a cover two defence makes is that a quarterback throwing there is throwing into a closing window, and that everything easier than that has been taken away.

What to test on the drawing

Find the seam yourself. Draw a vertical up the right hash from an inside receiver and mark who covers it at eighteen yards. If the answer is the middle linebacker, animate him getting there.
The corner's first three yards. Squatting at three is what makes the flat impossible and the deep sideline available. Draw him turning and running, and look at what he left.
Rotate one safety. Drop one to the middle of the field and the shell becomes single-high. Save both, and let the group see how differently one route reads against each.

Open the cover two shell in the designer, put the formation you actually face on top of it, and see which of the two safeties has too much ground to cover.