The Chiefs Have Long Been Quietly Emphasizing Defense. Now It Won Them a Super Bowl. (2024)

“In Spags we trust.” That was the mantra for the Chiefs throughout the postseason, but let’s be honest: Kansas City had no choice but to put its trust in Steve Spagnuolo, the 64-year-old defensive coordinator who secured his record-breaking fourth Super Bowl ring as a coordinator in the Chiefs’ 25-22 win over the 49ers. The 2023 Chiefs offense wasn’t bad. It just wasn’t very good—not based on the lofty standards Andy Reid and Patrick Mahomes have set over the years, at least. And certainly not based on the standards set by recent Super Bowl winners. These Chiefs were the first team since the 2015 Broncos to win a title with an offense that ranked outside the top seven in expected points added per play, according to TruMedia.

Even the greatest quarterback in the world couldn’t turn this young, inexperienced roster into more than an above-average unit. So for the first time since Mahomes took over the starting job in 2018, Kansas City’s defense was better than its offense—and it was better by a significant margin.

That was true again on Sunday. San Francisco may have lost the game, but the Niners defense won its individual battle with the Chiefs offense. Kansas City scored just 19 points in regulation. The offense averaged minus-0.06 EPA per play. Mahomes averaged 6.6 yards per dropback, and the Chiefs’ designed runs produced a success rate of just 33 percent. Mahomes was better than the numbers suggest, and his scrambling in the second half accounted for most of Kansas City’s successful runs on the night. But it was a one-man show from the Chiefs quarterback (with some assistance from his tight end) on offense. The defense took care of the rest.

The Chiefs held the 49ers to their third-worst offensive performance of the season by yards per play and EPA per snap. San Francisco’s ground game averaged a season-low minus-0.30 EPA per run. Shanahan’s offense hasn’t been that inefficient since last season’s NFC championship in Philadelphia, when the 49ers had to play without a quarterback for half the game. And we haven’t seen this version of the Niners offense stifled like this outside of the rain-soaked game in Cleveland, in which Brock Purdy couldn’t grip the ball, and a stinker against Baltimore on Christmas, which included five turnovers.

It became apparent early on this season that Kansas City’s defense would have to do most of the team’s heavy lifting. There were growing pains across the offense, as Mahomes and Reid tried to get a young receiving corps up to speed. So Spagnuolo’s defense had to be the linchpin that helped the team keep pace in the standings. Kansas City finished the regular season ranked fifth in EPA allowed and second in points surrendered. But this defensive emphasis predates this season. The regression we’ve seen from the offense, which dropped from first to 11th in EPA between 2022 and 2023, wasn’t planned obsolescence. But rather the front office, led by general manager Brett Veach, made a conscious decision years ago to strip parts from the offense and use the extra resources gained to stock up on the other side of the ball.

The 2022 offseason served as a prologue to this championship run. In March that year, the Chiefs dealt Tyreek Hill to Miami for five draft picks (including a 2022 first and a 2022 second). The move fundamentally changed how the offense would operate, but Veach believed it would free up the money to improve a defense that had gotten old.

“When we looked at this offseason, I think on our agenda was to add talent to the defensive side—whether it be defensive line or it be in the secondary—and take care of Tyreek,” Veach said a month after the trade. “It became obvious as the free agency started that it was going to be tough to do both. … So when we took a step back, and we figured, ‘How are we going to get better on both sides?’ That’s why we decided [trading Hill] was best for us.”

The 2022 draft was a week after that Veach press conference. And armed with those extra picks, Kansas City went heavy on defensive prospects, taking cornerback Trent McDuffie, edge rusher George Karlaftis, safety Bryan Cook, linebacker Leo Chenal, cornerback Joshua Williams, and defensive back Jaylen Watson. All six players were key contributors this season.

The defensive secondary has undergone the most significant transformation over the past two years. It went from a veteran-led bunch, featuring leaders like Tyrann Mathieu, Daniel Sorensen, and Charvarius Ward, to a younger, more athletic defensive backfield. L’Jarius Sneed, a fourth-round pick in 2020, is the only defensive back still on the team who started on the 2021 defense.

Drafting a bunch of good players is one way to quickly retool a defense, but the coaches also have to do their part in getting them ready to play, as Spagnuolo pointed out last Monday. “It says a lot about our assistant coaches. The guys that work with these young players that don’t get a lot of reps during the week and then all of a sudden have to go into the game,” he said. “If they’re performing well, it means somebody got them ready the right way. The staff that we have defensively is outstanding.”

Chiefs safeties coach Donald D’Alesio says the team’s practice approach has been the key in the rapid development of this young secondary that also has a lot put on its plate by this staff with all of the exotic pressures and coverage disguises Spagnuolo dials up.

“The way we practice is pretty unique,” D’Alesio said days before the game. “In the sense that we’re big on walkthroughs. We do a bunch of walkthroughs. And we always have two groups. So the first group’s getting all the work, and then I’m down there with the second [team], and we’re doing the same thing that first group is doing, but [with] a little less tempo, so they’re able to step through it and learn it.”

Spagnuolo has lauded his defense for its intelligence numerous times over the past few weeks, and that intelligence was put to good use on Sunday against San Francisco’s top-ranked offense. Kansas City put together a complex plan, with different fronts and coverages designed to not just defend, but to attack what the 49ers do best. And that, of course, starts with Christian McCaffrey and the run game. The plan called for a steady diet of early-down blitzes, with linebackers and safeties aggressively plugging gaps in the run game.

“We know how tough that team is stopping the run,” said safety Justin Reid, who signed with Kansas City during the 2022 offseason. “You’ve got to match physicality with physicality.”

The Chiefs blitzed on over half of their defensive snaps, per Next Gen Stats. After the game, Sneed told me that the blitz-heavy approach was designed to stop the run. “We just wanted Brock to throw the ball,” he said.

And throw the ball he did—to little success. Purdy went 1-of-5 for 19 yards on passes of over 20 air yards, according to Next Gen Stats. He averaged just 3.1 yards per attempt against Cover Zero calls. The 49ers led the NFL in total EPA on under-center plays during the regular season. Against the Chiefs on Sunday, they averaged minus-0.37 EPA per play on 33 under-center plays. The under-center offense is a foundational piece of the Shanahan scheme—at least on early downs—and was the least efficient part of the offense. Shanahan caught some heat after the game for not running the ball more in the second half, but it’s difficult to run the football against these looks the Chiefs were playing.

At times, the Chiefs put six defenders on the line of scrimmage with just one linebacker playing off the line, reminiscent of the Patriots’ defensive game plan against the Rams in the Super Bowl in 2019. Kansas City hadn’t used that defensive front previously this season.

“We put a little of that in to try to give a different picture to the offense,” Justin Reid said after the game. “We keep it interesting, man. You never know who’s going to be playing where in Spags’s defense.”

The 49ers couldn’t pick up what Spags was throwing at them all night. The Chiefs finished the game with a season-high nine unblocked pressures. Kansas City made it difficult on Shanahan by using looks it hadn’t put on tape all year, linebacker Nick Bolton said after the game. One of those looks came on perhaps the most important defensive play of the game: a stop on third-and-4 in overtime with the 49ers knocking on the door of a go-ahead touchdown.

“Coach Spags did a good job of mixing up some of our stuff in the red zone and running some stuff we didn’t really run down there all year,” said Bolton. “We had a zero blitz that we hadn’t typically run in the red zone … he fired it right there, and it came up beneficial for us.”

It takes a lot of guts to call an all-out pressure with a Lombardi Trophy hanging in the balance and only 4 yards to go for the offense to move the chains, but Spags showed that his players’ trust in their defensive coordinator is reciprocated. The Chiefs had gotten to that point with a boldly aggressive (but intelligent) approach on defense. That wasn’t going to change on the biggest play of the season.

“I mean, that’s what we do, baby,” Justin Reid said after the game. “We’re gonna pressure. From left, right, center, in whirlybird fashion. From all over the place, we’re gonna pressure.”

The 49ers pressured Purdy all night, throttled the vaunted San Francisco run game, and made Shanahan’s offense play left-handed. It was a comprehensive performance by a defense that has long taken a backseat to Andy Reid’s offense and Mahomes’s brilliance. But not this time. Not this season. These Chiefs were built to be a defensive-first team, and it won them a championship. A little trust can go a long way.