The key to getting to (or winning) the Super Bowl: the No. 1 seed

Analysis by Harry Enten, CNN

(CNN) — The No. 1 seed in the playoffs is the NFL’s equivalent of unlocking Star World in Super Mario World on the old Super Nintendo. When you get the top playoff seed in a conference thanks to a strong regular season, you get to skip a round – or level/world if we’re keeping with the Mario analogy – and play all conference games at home in the postseason.

The Kansas City Chiefs have already clinched that this year in the AFC, while the NFC remains way too close to call – the Detroit Lions and Minnesota Vikings ahead of a winner take all Sunnday night matchup in Week 18 – in a chase for the NFC’s bye.

The No. 1 seed is pivotal: the top-seed makes the Super Bowl slightly more often than all other seeds combined.

Why are No. 1s so successful? In some ways, it is obvious. They need to win one fewer playoff game to reach the Super Bowl than all the other playoff teams in their conference and are often quite good at football.

Interestingly, merely playing at home – the famed “home-field advantage” – may not matter very much in the No. 1 seed’s success, however.

Let’s take a look at every completed NFL season in the last 25 years. The teams that have gotten the top seed have won 26 of 50 (52%) conference titles. Given that there were 308 teams fighting over those 50 spots, this 52% is amazingly high. By probability alone, the one seed should make the Super Bowl about 15% of the time.

The bye, itself, is likely quite an important component of the No. 1 seeds’ success; a bye means a team has to win two games to reach the Super Bowl instead of three games.

Consider the simple math from 1999 to 2024. There have been 1,568 winning streaks during the regular season of at least two games. Only slightly less than half of those streaks (780) were extended to three games or more.

This importance of the bye makes the number one seed even more key than it used to be. Up until 2019, the top two seeds in each conference got a bye. Now, it’s just the No. 1 seed.

About three-quarters (32 of 42) of teams that made the Super Bowl got a bye (first or second seed) from 1999 to 2019 made the Super Bowl. This included 52% of teams that were the one seed and 24% who were the two seed.

Over the last four seasons, four of eight (50%) of No. 1 seeds made the Super Bowl. Exactly zero of eight No. 2 seeds made the Super Bowl. This includes my Buffalo Bills who have been the second in the AFC three of the last four years.

Now, it is possible that the lack of second seeds making the Super Bowl since the elimination of No. 2s getting the bye is due to chance – though it is unlikely. For my sake, I hope it is just bad luck as the Bills are almost certainly going to be the second seed again.

Of course, the success of the first seeds in making the Super Bowls isn’t merely about the bye. The No. 1 seed is often very good.

We can see this by looking at the margins the one seeds won their regular season games by and the toughness of their schedules. There are a lot of systems that help us combine these stats, but I’m going to use the Simple Rating System (SRS) from Pro-Football-Reference because it is widely used.

There have been 27 instances where a team was the top seed and were the best team in their conference per SRS. The clear majority of the time (18 out of 27, or 67%) these teams went on to play in the Super Bowl.

When the No. 1 seed was not the same team that led in SRS (i.e. they weren’t the best team when accounting for margin of victory and strength of schedule), they only went on to the Super Bowl eight of 23 times (35%).

This would suggest that a good portion of the reason No. 1 seeds do so well in the playoffs is that they are the best team in their conference. When they aren’t the best team (again, by SRS), their chance of success is far lower.

This could be bad news for the Chiefs who don’t lead the AFC in SRS. They’re third behind the Baltimore Ravens and my Bills. This is why I noted previously that the Chiefs were “the luckiest good team ever.”

Chiefs fans might want to argue that a “win is a win” and Kansas City was able to win last season despite struggling in SRS. That is, they’re the outlier who comes up big when the game is on the line.

You might think this Bills fan would dismiss this line of thought out of hand, but I’m not going to. The Chiefs do lead the league in Elo ratings (a slightly different measure of a team’s strength), which takes into account the Chiefs’ past success and weights winning – regardless of the margin – more heavily.

This Elo measure from the esteemed Neil Paine is usually highly correlated with SRS. When I asked Paine about this disparity in the Chiefs’ rating between Elo and SRS, he said the Chiefs are “sort of the perfect outlier.”

The Lions, who are the favorite to get the number one seed in the NFC, lead that conference in both SRS and Elo. They should be a clear favorite to reach the Super Bowl – that is, if they do get the number one seed.

But what about the fact that the Chiefs and probably the Lions will get to play two home games in the postseason? Isn’t home-field advantage important?

The 2023 Chiefs may be instructive in answering this question. They won two games on the road in tough playoff environments. They weren’t alone.

Indeed, playing at home doesn’t seem to provide as big of an advantage as you might think. Over the last six seasons – including the 2020 Covid season when many teams didn’t have a home crowd – the home team won 53% of regular season games. This season, home teams have won the same 53% of regular season games.

This is a drop-off from the 1999 to 2018 baseline when the home team won 57% of their games.

While the decline may not seem big, it’s quite significant. We’re talking north of 1,500 games since 2019 and north of 5,000 games during the prior 20-year stretch.

A slew of different reasons for this differing impact of home field have been offered, such as better visitor locker room facilities (i.e. less stress on the away team) and the increase in tickets being sold on the secondary market (i.e. away team fans can more easily buy tickets) in recent years.

Whatever the exact reason, I’m just hoping Bills fans buy up a lot of seats if they have to face the Chiefs in the playoffs. Otherwise, Kansas City may end being one of the No. 1 seeds to make the Super Bowl – and maybe win a historic three-peat in the process.

The-CNN-Wire
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