What’s wrong with the Chiefs’ defense? How Chris Jones’ position switch, injuries have led to 2021 stumble

The Chiefs sputtered once again in a tough test against an AFC foe. They lost to the Bills 38-20 on “Sunday Night Football” and were clearly outplayed during the game. That has led to a lot of criticism for the Chiefs, and Patrick Mahomes is the target of a good chunk of it.

That’s entirely fair. Mahomes had a tough outing against a Bills defense that was built to stop him, and he was uncharacteristically inaccurate throughout the night.

However, the bigger problem was a familiar one for the Chiefs; their defense simply couldn’t stop Buffalo’s offense.

The Bills moved down the field with ease against the Chiefs. They totaled 436 yards of offense and outgained the Chiefs by 44 yards despite running 25 fewer plays than them. Buffalo averaged 8.1 yards per play during the contest.

This is nothing new for the Chiefs’ defense. They have allowed at least 29 points in all five of their games during the 2021 NFL season and possess the NFL’s worst scoring defense — 32.6 points per game allowed — as a result. They are allowing the second-most yards per game league-wide at 437.4 as well. Only the Seahawks’ mark of 450.8 is worse.

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What exactly is wrong with the Chiefs defense? There are a variety of issues that have plagued the team through the first five games of the season, and they are a big part of the reason that the team has stumbled to a surprising 2-3 start.

The Chiefs’ run defense is among the worst in the league

It was easy to write off the Chiefs’ struggles against the run after the first two weeks of the season. As coach Andy Reid explained at the time, there was a reason for that.

“We played the two best run teams in the league back-to-back,” Reid said after the Chiefs’ games against the Browns and the Ravens. “We need to do better, and that is the bottom line. The way that I see it, we need to make sure that we tackle when given the opportunity and then get off blocks. Those are the two primary things.”

However, those improvements have yet to come. Through five weeks, the Chiefs continue to be one of the weakest run defenses in the NFL. They have allowed an average of 141 yards per game (fifth-most in the NFL) and have allowed at least 100 rushing yards in four of their five games.

So, what’s the issue? Well, as Reid mentioned, they’re not tackling well. And in particular, the Chiefs have struggled to bring down running quarterbacks. They have allowed a league-high 236 rushing yards to quarterbacks this season and have allowed quarterbacks to rush for three touchdowns, which is the second-most in the NFL behind only the Texans.

Additionally, the team hasn’t gotten strong play from their nose tackles this year. Derrick Nnadi has struggled mightily in 2021, as his Pro Football Focus run defense grade has declined from 81.7 in 2020 to 40.8 so far in 2021.

Meanwhile, Mike Pennel, a 332-pound run-stuffer who played nearly 30 percent of the snaps at defensive tackle last year, signed with the Falcons in free agency. The Chiefs have struggled to replace his rotational impact and that has been exacerbated by Nnadi’s issues.

Those problems are why Kansas City entered Week 5 with a PFF grade of 29.2 against the run. That was easily the worst mark in the NFL and ranked 10 points lower than the second-worst team (Arizona). And there’s another issue with the team’s interior line: they’re missing their best defensive tackle from the last five years.

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Chris Jones’ position change

Jones may not be gone from the Chiefs, but he moved to the edge for the team. The goal of this switch was to pump up the team’s middling pass rush, which achieved a 24.6 pressure percentage (12th in the NFL) and two sacks per game (19th in the league) during the 2020 season.

Early, it looked like Jones’ position switch would be a good thing. He totaled two sacks against the Browns in the season opener and looked like a nice partner for Frank Clark. However, he has had some issues changing positions, as one would expect.

Jones’ production certainly can translate to the edge. The only issue is that he has played on the interior for so long. He spent the first five seasons of his career playing on the interior and made the Pro Bowl in his first two seasons playing primarily in the 4-3 alignment. Now, he’s learning a new position and there have been some growing pains.

Take his performance against the Ravens, for instance. Jones was tasked with helping slow down the read-option game with Lamar Jackson, and he had a tough time doing so. He wasn’t used to playing as an unblocked player off the edge, and as a result, he had trouble trying to decide how to attack the play downhill and ended up flat-footed, at times. That’s an issue he didn’t have at defensive tackle.

That’s not Jones’ fault by any means; few players can contain Jackson well. It’s more about the fact that it’s taking time for him to get comfortable on the edge. The Chiefs had to know it would take him some time to adjust to the new position, but that time has caused some problems for Kansas City, especially since they’ve struggled to replace him on the interior.

By the end of the year, Jones’ problems well may be cleaned up. But at least in the first month of the season, his presence — or lack thereof, at times — has impacted the Chiefs.

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Key players like Frank Clark, Tyrann Mathieu have missed time due to injuries

Of course, the fact that Jones has missed time has been a problem for the Chiefs. In fact, they’ve missed a lot of starters throughout the season due to injury.

Jones was inactive against the Bills because of a wrist injury. The team was also without starting cornerback Charvarius Ward, who was dealing with a quad issue. Those absences were felt, as the Chiefs logged zero sacks and just one quarterback hit against Allen on Sunday night.

The Chiefs have also been shorthanded in previous weeks. Edge rusher Frank Clark has played in just two of the team’s five games because of a hamstring injury. Safety Tyrann Mathieu missed the first game of the season because of a stint on the COVID list. Linebacker Willie Gay played his first game of the season against the Bills after being sidelined for the first four weeks with a toe injury.

All of these players are valuable assets for the Chiefs’ defense, and it could be argued that Clark, Jones and Mathieu are the unit’s best players. Meanwhile, Ward played more snaps than any Chiefs corner last year, so it’s clear that Steve Spagnuolo and Co. trust him as a top option on the outside.

Missing those key contributors would hamstring any defense, so it’s not a surprise that the Chiefs have struggled at times. Perhaps they’ll improve when they’re fully healthy, but they may need to make some changes yet, as some of their players are simply not producing.

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Daniel Sorensen has had trouble in coverage

Sorensen has long been a part of the Chiefs’ defense. He signed with the Chiefs as an undrafted free agent in 2014 and has played in 98 games with the team, including 36 starts. He was once a solid starter, but through five games in 2021, he has struggled.

In the first four games of the season, Sorensen allowed a passer rating of 127.9 on 14 receptions (good for the fourth-most in the NFL). The passer rating mark is the worst of his career, per Pro Football Focus, and it’s the first time since 2018 that he has allowed a passer rating above 100.

Sorensen’s passer rating is so high because he has been allowing a lot of big plays. That was on display Sunday night against the Bills when he allowed a 53-yard touchdown to tight end Dawson Knox. He covered Knox well for a while, but he simply let the tight end get behind him as Josh Allen extended the play.

As a safety, Sorensen simply can’t make a mistake like that; he’s the last line of defense on deep patterns like that. He’ll have to clean that up moving forward.

As it stands, those issues against the pass are why Sorensen entered Week 5 ranked as the third-worst safety in football among PFF’s 78 qualified players at the position. If the Chiefs want their back-end coverage to improve, they’ll need Sorensen to regain form and play a bit safer in coverage. Otherwise, they’ll need to consider giving more snaps to Juan Thornhill and demoting Sorensen to the backup slot.

There’s still plenty of time for the Chiefs to get things worked out on this side of the ball, but the longer they remain in the AFC West basement, the direr their need for defensive improvements will become.