Conference Championships Preview: expect closer games than we've seen in recent past
The 2022 AFC and NFC title games represent the tightest point spreads this century
Then there were four. The NFL conference championships kick off on Sunday, and to be honest, it feels like the most deserving quartet of teams are in it.
The San Francisco 49ers will take on the Philadelphia Eagles at Lincoln Financial Field in the NFC Championship while the Cincinnati Bengals and Kansas City Chiefs will meet at Arrowhead for the second straight year vying for the AFC title. All four teams were consistently the cream of the crop this season, and it shows in the betting odds and their records.
Vegas has the Eagles and Chiefs as the two most likely teams to come out of this weekend’s games, but only a few points separate each of the teams. Both games feature spreads of less than a field goal for the first time since the 1990s.
Depending at what book you look at, the Philadelphia Eagles opened as one-point favorites over the 49ers for the NFC Championship Game before moving to around 2.5 as of this writing. Kansas City opened as a 2.5-point favorite over the Bengals, but that line has flip-flopped between the two teams all week. As of now KC is a one-point favorite.
These historically tight lines mean the Super Bowl favorite comes into Championship Weekend with odds longer than +200, which translate into a little over 30 percent implied probability of winning it all. Philadelphia has the healthiest chance at nearly 60 percent to win this weekend, and 30 percent to take home football’s most prestigious prize in two weeks.
Nobody would consider any of these four teams to be frauds. The Eagles and Chiefs finished with the best record in the NFL at 14-3, followed by the Niners at 13-4 and the Bengals at 12-41. But looking beyond what actually played out on the field, all four teams are who we thought they were given their underlying numbers.
According to the concept know as Pythagorean expectation, the conference championship game participants represent four of the top six teams in expected wins based on how many points they scored and allowed throughout the season.
A common theory among sports statisticians is that a team's winning percentage can be estimated by its points for and points against irrespective of their actual winning percentage.
The pythagorean formula states that the percentage of games a team will win across a given season should be proportional to the ratio of the square of the points scored by the team in that season, divided by the sum of squares of the points scored by the team and allowed across the whole season2.
The principle, made famous by baseball sabermetrician Bill James, insinuates teams that win a game or more over what the Pythagorean theorem would project tend to regress the following year; teams that lose a game or more under what the Pythagorean theorem would project tend to win more the following year.
So what does it tell us about this year’s playoffs?
According to this analysis3, the 49ers should be the odds-on favorites to lift the Lombardi Trophy in Glendale next month. That’s thanks to their league-leading 173 point differential in the regular season. While they did slightly overachieve their expected win percentage they still had the highest Pythagorean win percentage of all 32 NFL teams. The Eagles, Chiefs and Bengals all had stellar seasons as well, but the numbers suggest they all overachieved by quite a bit more than San Francisco.
Also, look away Vikings fans. Minnesota is an obvious candidate for regression as it overachieved its Pythagorean expectation by a whopping 27 points. Don’t be surprised if the Vikings finish under .500 next year
For what it’s worth, my favorite weekend of the NFL schedule is the conference championships — it’s the final game any team will play in front of its home fans so you know it’ll be as raucous as it can possibly get. Especially if we’re talking about Philly where I’m certain they care about the 49ers’ Pythagorean win record.
I wouldn’t want to be wearing red at the Linc this Sunday. But either way let the games begin.
Their Week 17 game against the Bills got canceled after Bills DB Damar Hamlin suffered a scary cardiac event while making a tackle in the game.
This is a concept which can help explain not only why teams are successful, but also can be used as the basis for predicting results in the future, and evaluating which teams are over-performing and under-performing.