ChiefsPlanet - Chiefs Steve Spagnuolo: The Man with Four Aces Up His Sleeve

Assessing the Chiefs Analytics
By
Seth Keysor

Quote:

It was supposed to be so simple for the Kansas City Chiefs as they prepared for the 2019 season: Get a defense that isn’t terrible, and the Super Bowl awaits.

That’s perhaps a bit of hyperbole, but it’s at least close to the truth. Led by quarterback Patrick Mahomes and head coach Andy Reid, the 2018 Chiefs scored more than 35 points per game and fielded one of the most productive offenses in history. No team held them below 26 points or truly stopped them over the entire season.

The Chiefs came agonizingly close to a Super Bowl berth — literally a few feet, as edge rusher Dee Ford infamously lined up offsides on what would have been a game-winning play in the AFC Championship — on the back of their historic offense, but down the stretch the defense proved to be a fatal flaw. Former defensive coordinator Bob Sutton’s crew couldn’t make stops, and the offense was consistently forced to score repeatedly for the Chiefs to win games.

The Chiefs’ D finished 26th in Football Outsiders’ DVOA last season (a defensive efficiency stat that takes context of every play and strength of opponent into account, explained in more detail here). Being so weak on that side of the ball was the primary reason for each of the Chiefs’ losses, as even when the team would score in bunches or held a lead late in the fourth quarter, it wasn’t enough.

The Chiefs lost center Mitch Morse and receiver Chris Conley to free agency in the offseason, but otherwise kept their offense intact. With another year to gel and Mahomes still developing, the assumption was that the offense would be able to stay nearly as dominant and perhaps somehow even take a step forward. Which meant that all the Chiefs needed was an average defense to be a clear Super Bowl favorite.

With 12 weeks complete in the 2019 season, something interesting has happened and gone largely unnoticed: One side of the ball has accomplished its goal — and it’s not the offense. By any reasonable measure, the defense has significantly outperformed its 2018 performance.

Yards and points per play/drive are obvious terms, but there are two other in-depth stats used here that are very important.

DVOA: As discussed above, this is a measure of efficiency that looks at every play and takes into account down, distance, field position, score and quality of opponent.

EPA Per Play: Expected points added per play, which is a reflection of how much more likely a team is to give up a score (if the number is negative) or score (if the number is positive) after a play. Obviously, the higher the number the better, but most defenses are somewhere in the negative.

All of these stats can be combined to help us get a much closer look at the defense than points per game or total yards allowed. While statistics can be misleading for individual players, for team performance in-depth stats such as the ones above do not lie: The defense has jumped from cellar-dweller to “average” in 2019.

One of the most important jumps has been in the pass defense, which has improved to the point of being very good at 6th in the league. Because pass defense has such a large effect on EPA, the Chiefs’ EPA per play allowed has made a sizable jump. It also has had a significant effect on their points allowed on a per-drive basis.

The Chiefs’ run defense hasn’t taken a large step forward, but it has at least managed to stop being historically bad the way it was last year. While such a marginal change seems insignificant, it’s enough to help swing EPA and yards/points per drive.

The Chiefs conducted a massive overhaul on their scheme this offseason, and the results have been generally positive. New defensive coordinator Steve Spagnuolo has been more creative and aggressive with the pass rush.

In addition to a pass rush that has been perhaps more consistent than last season (despite losing exceptional players along the edge), the Chiefs have seen a large jump forward in their secondary. Free agent Tyrann Mathieu and draftee Juan Thornhill have been a massive upgrade at the safety position, and the much-maligned cornerback group has generally played well enough to force quarterbacks and receivers to make good plays if they want to move the ball through the air. This is in significant contrast with last year, when blown coverages were routine.

Had a stranger approached me this preseason and asked, “Seth, if at the bye week the Chiefs will have the 14th-ranked defense by DVOA and 6th against the pass, what do you think their record will be?” I would have had a very simple answer (outside of, “Um, who are you?”): They’d be at least 9-2 with an outside shot at being undefeated. The hope was to have a respectable defense, and the Chiefs now seem to have that.

So why are the Chiefs 7-4 and in the midst of what many would call a disappointing season? The answer lies on the other side of the ball. Looking at the same statistics for the offense as we did for the defense, a troubling pattern emerges.

The Chiefs’ offense has been very good in 2019, but it has been significantly less dangerous than it was in 2018. EPA per play and points per drive are particularly noticeable. The Chiefs rushing DVOA has taken a considerable drop, which may be a point in favor of those who believe in the run game’s value. The offense averaged .092 expected points added per rush in 2018. In 2019, the rush game has actually had a negative value at minus-.023 expected points per play. That’s worth re-reading: The run offense has hurt the Chiefs’ chances at scoring this year rather than helping. Assuming 25 carries per game, that’s a swing of 2.875 points per game.

Despite the problems with the run game, the Chiefs’ fall from historically good as a passing team to merely “very good” carries the most impact. The Chiefs averaged .457 expected points added per play passing the ball in 2018. In 2019, that number has fallen to .325 expected points per play. Assuming 40 passing attempts, that amounts to 5.94 points per game.

So what has changed? Why are the Chiefs not what they were last season, or even all that close? There are a few factors at play, and the most frustrating of them has been injuries. The most important players on Kansas City’s offense are Mahomes and receiver Tyreek Hill. Both of them have missed significant chunks of time this season, and Mahomes has played a majority of the season on a bad ankle. Between the two of them, they have missed nine games and have been together on the field for the equivalent of less than two full games.

Mahomes’ injuries have affected the offense more than any other factor. Being hobbled robbed Mahomes of his usual ability to move inside and outside the pocket to avoid rushers.

Mahomes also struggled with consistent accuracy while his ankle bothered him, as he was unable to put weight on the foot when throwing, especially on the run.

However, the impact of Hill’s absence to the offense cannot be overstated. Hill is not just a player who forces defenses to alter their coverage strategy throughout the game with his speed. He’s also exceptional at gaining yards after the catch and is one of the best contested-ball receivers in the NFL.

This touchdown came on 3rd-and-21. Hill’s ability to take bad situations and turn them into wins for the offense has been missed nearly as much as Mahomes’ ability to move around with ease.

The combination of Mahomes’ and Hill’s injuries has been bad enough, but the Chiefs have also dealt with left tackle Eric Fisher being out for an extended period. While he appeared less than 100 percent healthy and struggled at times against the Chargers in his return, Fisher’s absence meant an increased number of plays in which Mahomes (or Matt Moore, when Mahomes was injured) faced pressure almost immediately.

Pressure that happens quickly makes the play almost certain to fail, and it happened at least several more times a game than normal with Fisher on the sideline. While that number may not seem significant, when the number of dropbacks in a game is limited to 40 to 50 times, it makes a considerable impact when an extra 2 or 3 are doomed.

The Chiefs’ offensive line has also taken a marked step backward along the interior this season with Morse now in Buffalo. Replacement Austin Reiter hasn’t played as well as he did last season, and neither has left guard Andrew Wylie. Their steps back, combined with Fisher’s absence, as made the pass protection more unstable. This has resulted in Mahomes looking more jittery in the pocket as he appears to not trust the protection.

A final issue in the Chiefs’ large step backward is their inability to run the ball. While run offense is much less efficient than pass offense and carries significantly less importance, it does have situational value in salting away leads or converting short-yardage situations. Additionally, the ability to create yardage in a bad situation is one of the most valuable in the league. Last season, the Chiefs had one of the better players in the league at doing so in running back Kareem Hunt.

Had Hunt been replaced with a healthy Damien Williams (as he was last season) or a healthy LeSean McCoy, the drop-off may not be as noticeable. However, the Chiefs’ running backs have struggled with injuries, and that has affected the offensive output overall.

It’s worth noting that the Chiefs’ offense has a turnover rate of .080 per drive, as opposed to .110 per drive last season. So the decreased production on offense has been despite being luckier in one aspect of the game that is often random. Conversely, the defense has benefited from turnovers less in 2019 (.136 per drive to .155 per drive last season). So the defense has been less lucky than the offense in 2019, but has still improved significantly.

Perhaps the greatest culprit in the Chiefs’ decrease in offensive efficiency this season has been red-zone offense. In 2018, the Chiefs averaged 5.69 points per trip to the red zone, first in the NFL. That number has tumbled to 4.71 points per red-zone visit, 17th in the league. The Chiefs have not executed at a high level in the red zone due to the issues discussed above, and Reid has made the problem worse at times with play-calling that is overly reliant on single options.

So what does all this data mean? The broadest point to be taken from this is that the Chiefs defense has in fact been what was hoped for heading into this season, and is good enough for the Kansas City to win the Super Bowl. The problem is that the offense has underachieved compared to expectations for a variety of reasons. That’s not to say the offense isn’t still superior to the defense, but it hasn’t been the force it was anticipated to be.

The good news for the Chiefs is that the injury issues that have plagued the offense could be resolved moving forward, and their own failures in the red zone are quite fixable. And if/when the offense regains something resembling its 2018 form, the defense it was waiting for last season has already arrived.