Chiefs by the Numbers: Reviewing Weeks 1 and 2

In this series, we’ll review the Kansas City Chiefs’ performance primarily using Next Gen Stats — along with any other advanced metrics that turn up during the season.

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Patrick Mahomes Next Gen Stats passing metrics

First, we’ll need to familiarize ourselves with some NGS statistical categories.

• Time to Throw (T-t-T) is the average time between the snap and the throw on every pass attempt. Sacks are excluded.
• Completed Air Yards (CAY) begins with Air Yards, which is the vertical distance from the line of scrimmage to where the ball is (or would be) caught. Passes thrown to behind the line of scrimmage are negative values — and when applicable, the depth of the end zone is included. Completed Air Yards (CAY) is the average Air Yards for completed passes.
• Intended Air Yards (IAY) is the average Air Yards for all pass attempts.
• Aggressiveness Percentage (Agr%) is the number of passing attempts made into tight coverage (where there is a defender within one yard of the receiver when the pass arrives) divided by the total number of attempts.
• Completion Probability (CP%) is the probability a pass will be completed. It is based on many factors — including the receiver’s separation from the nearest defender, where the receiver is on the field, the quarterback’s separation from the nearest pass rusher at the time of the throw — and more.
• Expected Completion Percentage (xCP%) uses a passer’s Completion Probability on every play to determine what a passer’s completion percentage is expected to be.
• Completion Percentage Above Expectation (+/-): A passer’s actual completion percentage compared to their Expected Completion Percentage.

Now let’s look at these metrics during Mahomes’ career. Throughout the season, we’ll update this table to show his evolution through the eyes of Next Gen Stats.

In this table, you can see how Mahomes (and the Chiefs’ offense) have evolved through his career.

2018-2020

Through the 2020 season, Mahomes was slinging the ball around the field with no fear. His intended air yards (IAY) was 9.2 per play. These numbers put him in the top echelon of quarterbacks who pushed the ball downfield — alongside players like Matt Stafford, Josh Allen and Jameis Winston.

It’s also worth noting that during this time, Mahomes’ aggressiveness percentage (Agr%) was between 11.4 and 12.2%. This puts him in the bottom quarter of quarterbacks during this time, along with players like Aaron Rodgers and Russell Wilson.

Was this about Mahomes himself — or was it because he was throwing to elite seperators like Tyreek Hill, Travis Kelce and Sammy Watkins? That’s something we’ll examine in the future.

2021

Last season, there were some drastic changes in Mahomes’ numbers His intended air yards were down 1.2 yards per attempt, his aggressiveness percentage was down 2.7% and his expected completion percentage was 2% higher than his actual completion percentage. All of these numbers were among the bottom quarter of NFL quarterbacks — with the likes of Ben Roethlisberger, Matt Ryan and Jared Goff.

Still, Mahomes still put up 37 touchdowns and 4,839 yards, leading Kansas City to a home AFC Championship game. If that was his down year, the Chiefs will be all right over the long term.

2022

Through the first two weeks of the season, we have seen a blend of the 2018-2020 Mahomes and the player we saw last year. Mahomes’ air yards are still down compared to his previous years — but through two weeks, he is in the middle of the pack when compared to the rest of the league’s quarterbacks. This is perhaps a sign that NFL defenses are evolving into forcing teams to beat them underneath — which is what Mahomes is doing.

Through the first two weeks, Mahomes' completion percentage is a whopping 4.6% greater than his expected completion percentage, while his aggressiveness is returning to what we saw in his first three seasons.

In both Week 1 and Week 2, Mahomes completed passes to 10 different receivers, doing most of his damage between five and 15 yards from the line of scrimmage. On passes of 20 or more air yards, Mahomes has completed only two of six passes, including the touchdown to Justin Watson. It would seem that early in the season, the Chiefs have been content with working underneath.

One stat that we will be watching over the next few weeks is Time to Throw (T-t-T). Through two weeks, it is at a very low 2.63 seconds — which might be a big reason why Mahomes isn’t throwing deep as often. Facing Los Angeles Chargers pass rushers Joey Bosa and Khalil Mack in Week 2 obviously didn’t help this number, either — but it is worth keeping an eye on this stat to see if the offensive line shifts to more of what it was in 2021.

Patrick Mahomes against the blitz

For the second straight week, the opposing team blitzed Mahomes at an unusual rate compared to recent years. A known blitz-killer, he shredded both the Arizona Cardinals and the Chargers when they came with additional pass rushers.

It’ll be interesting to see if teams continue to test Mahomes’ ability to beat the blitz.

Wide receiver performance

Against the Chargers, the only player to really garner any true separation was tight end Travis Kelce — although wide receiver JuJu Smith-Schuster has looked fine in the short-to-intermediate routes with an average separation of 3.3 yards per route run.

The weak spots seem to be the team’s speed receivers. Mecole Hardman and Marquez Valdes-Scantling are on the team to create plays down the field — and according to NGS, neither are doing a very good job.

Andy Reid and going for it

Kansas City’s head coach has often been criticized for his decision-making on fourth down. On Thursday, we saw another example, when Reid chose to kick a field goal from the 1-yard line to start the fourth quarter. By all advanced metrics, it was a bad decision.

A touchdown over a field goal would have increased the Chiefs’ win probability by 16.9% — while a failed conversion would have decreased the win probability by 9.3%. The analytics overwhelmingly said that going for the touchdown was the right decision.

Even worse, Kansas City received an unsportsmanlike conduct penalty on the ensuing kickoff, giving Los Angeles the ball at the 40-yard line. Luckily, the Chiefs were bailed out by cornerback Jaylen Watson’s pick-six — but at the time of the interception, the Chargers’ win probability had increased to 74.6%.

Kicking the field goal was the wrong choice. The Chiefs were lucky that the decision didn’t come back to burn them.

The bottom line

Through Week 2, the Chiefs are exactly where they need to be after dominating the Cardinals and grinding out a great win against the Chargers. The offense needs some time to gel, but the early returns have been positive. My goal was for the team to begin the season 5-3. Kansas City is well on its way to that record.

Not too shabby.