Coverage has and continues to evolve over time. Earlier versions of zone coverage were more strict, symmetrical and easy to exploit. As offenses found ways to beat them, their counterparts had to adapt.

Defenses have gotten smarter over the course of football history and have created better rules and adjustments to help solve the problems that basic coverage have. An evolution most know about would be the Tampa 2. An inside linebacker runs a deep middle zone to help take away the seams and dig routes that offenses had success with.

Zone coverage splits the deep parts of the field between two, three or four deep defenders. What’s happening underneath them, and the responsibilities of those deep defenders can be adjusted to help confuse the quarterback and take away strengths or frequently used concepts of the offense.

Some coverages can apply man principles to zone coverage. How the routes are distributed throughout the coverage on the snap of the ball can create man to man responsibilities.

The same way that offenses have route adjustments based on coverage, the defense has coverage adjustments based on the routes. Both teams trying to solve what either is trying to accomplish is what makes Sundays so fun and so impressive. And part of why teams have scripts to start out.

As Travis Kelce said, the Chiefs aren’t executing against cover 2 looks. The Bills game was not pretty, but it’s more than just a blanket statement when he says they’re struggling against the coverage. Some of the principles being applied to cover 2 and other coverages are part of their struggles as well (I may go in depth further on that sometime).

Okay back to regular programming.

Here are some trends from the Bills game.

Coverage Trends

If you’ve been following these weekly trends articles at all, you’ve heard me talk about middle field open and middle field closed coverage.

Here’s a screenshot of a middle field open coverage:

Middle field open means that no one is occupying the middle of the field deep. That would be cover 2 (the latest curse word in Kansas City) and cover 4 (4 deep coverage that has some man to man principles). You can also play one half of the field cover 2 and the other half cover 4.

There’s a variation of cover 2 the Bills used that can make it look similar to cover 4. The Bills used a coverage called 2 Read at times that allows corners the ability to still be involved in coverage if there’s no action in their zone, the flats. The end result can look a lot like cover 4 if routes are vertical.

The Bills were in middle field open coverage for 55 percent of pass plays this week.

Here’s a screenshot of middle field closed coverage:

Middle field closed means that a safety is occupying the deep middle of the field. It’s likely cover 1 (man coverage, free safety in the middle of the field) or cover 3 (the deep part of the field split in thirds).

The Bills were in middle field closed coverage 45 percent of pass plays.

The First 15 Plays

The first 15 plays are scripted plays to get an idea of how teams plan to defend you. The script is followed until there’s special situations like third and short, and goal plays, etc.

The Chiefs used five different personnel groupings in the first 15:
11
12
21
21 Jumbo (Cameron Erving on the field as a 6th OL)
22

They called seven runs and eight passes. They gained only 26 yards. Not exactly how you want your early script to play out.

They lined up in 10 different formations, but used different motions on a few of the formations they doubled up on.

Tyreek Hill, Travis Kelce, De’Anthony Thomas and Albert Wilson all motioned at least once.

The Bills were in middle field closed coverage on all but one pass play.

Chiefs Offense

This was the most used formation by the Chiefs this week:

They had used this formation only five snaps in the first 10 games of the season.

For the first time all season, the Chiefs didn’t use this formation:

The Chiefs didn’t use 13 personnel all game for the first time all season.

They were in 11 personnel for 66 percent of snaps and 12 personnel for 25 percent of snaps.

The Chiefs ran eight run-pass options (RPOs), throwing four and running four. All eight of the plays had run designs to the right should Alex choose to hand it off. All of the RPOs were in the second half.

The Chiefs had only two explosive plays the entire game.

Bills Defense

The Bills played no snaps in base defense the entire game.

They were in nickel for all but one snap. The one snap they were in dime, they blitzed.

The Bills sent five or more rushers on 23 percent of charted snaps. One of the Chiefs’ explosive plays came against a five man pressure.