Athleticism Is a Major Component of KC Chiefs’ Defensive Improvement

The eye test indicates that this is the most athletic defense the Chiefs have had in the Steve Spagnuolo era, and it's backed up by metrics and the on-field product.

In years past, Steve Spaguolo's defensive unit had gotten off to slow starts before coming on strong to end the season. However, 2023 is different, as the Kansas City Chiefs have one of the NFL's best defenses. While defensive structure and philosophy are complicated, the Chiefs' improvement on the defensive side of the ball is more straightforward than that. 

Their personnel is more athletic and faster than in previous years, which allows Spagnuolo to use his creative designs as a trump card instead of a necessity.

Bill Barnwell of ESPN calculated the average age of every NFL team's units, weighted by snap counts. By that metric, Kansas City has the youngest defense in the entire NFL. This was a transition made over the last two years. The Chiefs have moved away from players like Tyrann Mathieu, Anthony Hitchens, Alex Okafor, Daniel Sorenson and others — staples of Spagnuolo's defense during his first three years in Kansas City — for younger players in their athletic primes.

Defense, at its core, is reactive. You have a play call or scheme you are running but once the ball is snapped, the defense must react to what the offense is doing. Having athletes who can close on ball carriers, eliminate angles and cover a larger area of the field helps prevent explosive plays from happening. That is something that the Chiefs struggled with early in Spagnuolo's tenure. They played a boom-or-bust defensive style, blitzing a ton to force negative plays. This year, while the Chiefs are still one of the best blitzing teams in the NFL, it has become an option.

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This was on full display during the final drive this past week in Germany. The Chiefs' defense didn't blitz on first and second down, only rushing four and having seven players in coverage. They forced an incompletion on both plays, setting up a critical third and fourth down for Miami to stay in the game. That's when Spagnuolo dialed up the blitz to force Tua Tagovailoa to throw an incomplete balloon on third down and scare him into dropping the snap on fourth down. All four calls would have been blitzes two years ago because that was the only way the Chiefs' defense could win. They can now be multiple and not tip the opponent off to what they are doing, making them terrifying to play against.

The Miami Dolphins matchup is the best showcase of the improved athleticism shown on defense. Tyreek Hill, Jaylen Waddle and the rest of Miami's offense have been running through defenses the entire season, especially creating yards after the catch and explosive plays. Kansas City limited Miami to one explosive pass all game and limited yards after the catch. For example, there was a slant route Hill ran on third down against Trent McDuffie. Hill won and had green grass in front of him but because McDuffie had the recovery speed, he immediately tackled Hill and limited him to only getting the first down.

Let's look at relative athletic scores (RAS) to quantify the improved team speed on defense. RAS measures a player's athleticism based on their pre-draft testing and compares it to other players at their position. The score is out of 10, with each individual metric also being compared on the same scale. On Sunday, Kansas City predominantly played 10 players in their back seven. Eight had a RAS score of over 9.2, which is elite. Mike Edwards was 7.48, roughly average. Bryan Cook wasn't able to test due to injury but judging by his touchdown runback, he'd probably be in the high nines on the RAS scale. That collection of athleticism creates an endless number of defensive possibilities.

Bryan Cook returns a Tyreek Hill fumble for a 59-yard touchdown (after a lateral from teammate Mike Edwards). Cook reached a top speed of 21.31 mph, the fastest play by a Chiefs' ball carrier this season.#MIAvsKC | #ChiefsKingdom
📱: Stream on #NFLPlus https://t.co/kbuNQC0uT9 pic.twitter.com/aLDaYjgj3r

— Next Gen Stats (@NextGenStats) November 5, 2023

Of course, the defensive players are great fits and super talented, but the team's speed and athleticism differentiate from years past. Spagnuolo always has a feeling-out process early in the year to see what works and what doesn't. With the versatility and athleticism of his personnel, there haven't been the kinks of years past. It has become a running comment that the defense gets the 'Spags bump' after Halloween and in the playoffs. The rest of the NFL should be even more terrified if that happens for this year's Chiefs team.

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