Could the Chiefs offense keep getting better?

It’s no secret that the Kansas City Chiefs are an offensive team.

Head coach Andy Reid and general manager Brett Veach have assembled an all-star lineup featuring arguably the league’s top quarterback, wide receiver and tight end — along with the league’s top right tackle — that has been terrorizing opposing defenses. Even before superstar quarterback Patrick Mahomes joined the team, the offense was putting up points at a level Kansas City fans hadn’t seen in quite some time.

And now they have spent a first-round draft pick on a running back. While some (like myself) have questioned the value of the move, it will very likely make the team even more efficient.

That got me thinking: Is there a limit to just how good an offense can be?

There’s only so much time — and so many drives — in a football game. And players are human. Even the best of them are going to drop an occasional pass, miss an occasional throw and so on. Finally, the NFL has a salary cap. Unless players are willing to take big pay cuts, there’s a limit to how many offensive stars a team can field. Is there a point when more offense weapons won’t help?

To start answering this question, I examined how efficient offenses have been over the past 20 years by charting their average Expected Points Added (EPA) on each play. During the last few seasons, how have the Chiefs fit into the picture?

A few things are worth pointing out here.

One is that offensive efficiency has been increasing over time; the dashed black line represents the league average offensive EPA each season. This should not be a surprise, because the league is constantly changing. In recent years, new scheme innovations — and perhaps more importantly, new rules — have led to offenses becoming more efficient than ever.

Another is that in recent years, the Chiefs have indeed been near the top — third in 2017, first in 2018 and second in 2019.

And finally, no team has ever been significantly above the 0.20 EPA per play. In terms of efficiency, the best offense since 2000 was actually the 2007 New England Patriots, followed very closely by the 2018 Chiefs.

You’ll recognize the 2007 Patriots as the team that finished the regular season 16-0 — and were just a few plays away from finishing as undefeated Super Bowl champions — before being foiled by the New York Giants team led by quarterback Eli Manning (and defensive coordinator Steve Spagnuolo).

The Patriots, of course, had quarterback Tom Brady, along with receivers Randy Moss and Wes Welker and second-year running back Laurence Maroney. We don’t have in-depth player grading data (such as from Pro Football Focus) on these players, so it’s hard to make direct comparisons to the corresponding players on the current Chiefs roster. But you’ll likely agree that Mahomes and company definitely compare favorably to them.

So, we know the historical ceiling for offensive EPA per play. But what about points scored?

Unless you’ve worked with the data a lot, it’s far harder to conceptualize how many points an offense will score solely from their EPA. But the record for points scored in a game was set all the way back in 1940, when the Chicago Bears beat the Washington Redskins 73-0 (ouch). Over an entire season, the record is 38.83 points per game, which was set by the 1950 Los Angeles Rams.

So we have our historical ceilings. But our offensive metrics say that offenses are improving each year. So shouldn’t our ceiling be rising?

To answer that, let’s use a different way of analyzing offensive success — this time, measuring a team’s performance relative to other teams in each season. To do this, we’ll use what’s called a Z-score — another name for standard deviations from average. Essentially this is a number showing how far above (or below) average a team performed in a given season. In this way, we can separate a team’s raw performance figure from the historical rise in offensive efficiency — for example, an EPA per play of 0.20 was more impressive in 2007 than it was in 2018.

This chart looks very similar to the previous one — but there are some key differences.

Now we see a clear peak for the 2007 Patriots, who were three standard deviations above average that season, compared to a Z-score slightly above two for the 2018 Chiefs. Even that is still impressive — but the chart shows us that over the years, many other teams have done as well or better.

While this may seem like a negative, this is actually a good thing. It means that it’s likely the Chiefs still haven’t reached their peak; just in the past 20 years, many teams have outperformed their peers by more than the Chiefs have. If the 2020 Chiefs turn out to be as dominant as the 2007 Patriots — and assuming overall offensive efficiency continues to increase — we’d expect an EPA per play of around 0.24. This may not seem like a big improvement from the 2019 team, but it would be. On a per-play basis, the offense would actually be almost twice as efficient.

We haven’t unearthed any great insight here — but I think it is still worthy to note that the Chiefs offense may not have hit its peak; many teams have had more dominant offenses. That said, expecting improvement in 2020 remains fairly unlikely; the chart shows few teams that maintained a high level of relative efficiency over many years.

But if the Chiefs continue to invest in offense, we may see them do just that.