The 2018 season felt like a breakout for the Kansas City Chiefs, an odd thing to say about a franchise that had won at least nine games in each of the previous five seasons.
Of course, there's no denying that Andy Reid & Co. took their game to a new level. The Chiefs finished the regular season 12-4 and won a playoff game for only the second time in the past 25 seasons. The Kansas City offense ranked first in the NFL in both points scored and yardage, the first time they've accomplished that combination (they did it in the AFL in 1966), and Patrick Mahomes won the league MVP in his first season as an NFL starter.
Despite the recent string of success, however, there are a few reasons to be concerned about the Chiefs taking a step back in 2019 and perhaps even missing the playoffs for only the second time since Reid took over as coach in 2013.
Regression is inevitable
If nothing else, impending offensive regression to the mean is a near-undefeated force the Chiefs will need to overcome.
Consider the Chiefs' 2018 offensive explosion, which was responsible for a majority of the team's success. They averaged a whopping 35.31 points, 425.6 yards per game and 6.84 yards per play, all of which were tops in the league. They finished in the top five in first downs per game (24.0), third-down conversion rate (47.2 percent), red zone efficiency (71.8 percent) and scoring margin (plus-144).
The Chiefs' offense totaled 66 touchdowns, which league history tells us is unsustainable. Each of the five offenses that scored 58-plus touchdowns in a single season from 2009 to 2017 suffered a large drop-off the next season. The average dip was 15.8 scores, or nearly one full touchdown per game. Those offenses were led by a who's who of the league's best passers in Peyton Manning (2013 Denver Broncos), Aaron Rodgers (2011 Green Bay Packers), Drew Brees (2011 New Orleans Saints), Tom Brady (2012 New England Patriots) and Matt Ryan (2016 Atlanta Falcons).
Even more incredible, of the 30 offenses that scored 50-plus touchdowns in a season over the past decade, only three increased their total the next season. All three were Patriots teams (2011, 2012, 2016). The average drop of everyone else was 13.3 touchdowns. Again, nearly one per game.
History suggests that the Chiefs will still rank near the top of the NFL in scoring but won't come close to their historic 2018 production. As we'll get to later, that could be a big problem.
The regression will likely hit Mahomes, too.