NFL Playoffs: Here’s who the Chiefs will most likely play in the divisional round

Holding the number one seed in the 2018 playoffs, the Kansas City Chiefs don’t yet know which opponent they will face when they play their first game at Arrowhead Stadium on Saturday, January 12 at 3:35 p.m. Arrowhead Time.

We know that it will be either the Baltimore Ravens, Los Angeles Chargers or Indianapolis Colts. But which one will it be?

There’s no way to know for sure, but as it turns out, one of these opponents is more likely than the others. This has to do not only with which teams are more likely to win their games this weekend, but also with how the NFL playoffs are constructed.

At each step of the playoffs, the highest-seeded remaining team always plays at home against the lowest-seeded remaining team. In the AFC wild card games this weekend — where the two top-seeded teams sit out — that means the Houston Texans (third) play at home against the Colts (sixth), and the Ravens (fourth) play at home against the Chargers (fifth).

We know the Chiefs will not play the Texans in the divisional round. If the Texans are one of the teams that remain after this weekend, they will have the highest seed (third) of the remaining teams, and would therefore face the New England Patriots (second) instead of the Chiefs (first).

By the same logic, if the Colts win against the Texans, they would have the lowest seed of the remaining teams (sixth) and would automatically face the Chiefs (first).

What this means is that the sixth seed is almost always more likely to play the first seed in the divisional round, and the third seed is almost always more likely to play the second seed. This is because it depends on the outcome of one game instead of two.

This will become more clear as we get down to cases.

Elo ratings published by FiveThirtyEight.com say that by their calculations, the Colts have a 44 percent probability to defeat the Texans — which means that there is a 56 percent chance that the winner of the Chargers-Ravens game will be traveling to Arrowhead the following week. The Elo ratings say that the Ravens have a 60 percent chance to win that game, so the Chargers have a 40 percent chance to win.

Then all it takes is some simple math to determine to probability that each of these teams will play at Arrowhead the following week:

• Colts: 44%
• Ravens: 60% X 56% = 34%
• Chargers: 40% X 56% = 22%

It seems counter-intuitive that the weakest team has the best chance to face the strongest team in the next round, but as we see here, this is precisely why it is so important to obtain the number one seed in the playoffs.

Back in the 1990s, Chiefs fans were conditioned to believe that the main advantage of the top seed was to play at home throughout the playoffs — and obviously that’s helpful. But as we see here, even if playoff games were conducted on a neutral field, there is a substantial advantage to having the highest seed in the postseason. If you have the first seed, the most likely outcome is playing the sixth seed in the playoffs. But if you have the second seed, the most likely outcome is playing the third seed.

This also means that the probability of both outcomes occurring — that is, the first seed plays the sixth seed, and the second seed plays the third seed — is zero. That’s because both of them are dependent on which team wins a single game: the wild card game between the third seed and the sixth seed. But until that game is decided — which is where we are right now — the probabilities hold.

As you know, Elo ratings aren’t the only way to assess the probable outcome of NFL games. I did the same math using three other systems — Sagarin ratings, SRS ratings and Bovada betting odds — here’s how the probabilities line up for the Chiefs:

Here’s the same data for the Patriots’ AFC divisional round game in Foxboro:

For the New Orleans Saints in the NFC — holding the first seed — here’s the math:

Here’s how it works out for the Los Angeles Rams (second) for their NFC divisional round game:

As you can see, there’s not a whole lot of difference in how these different systems assess the probabilities for each matchup. But we consistently see that the most likely opponent for the first and second seeded teams are the third and sixth-seeded teams. This will tend to be true in most seasons because point spreads among playoff teams will tend to be low.

If we wanted to, we could calculate this all the way through the postseason. But as each round is played, the results of each game affect the probabilities of a win in each successive game. This makes the math more difficult.

Thankfully, we don’t have to do that.

FiveThirtyEight runs 100,000 simulated seasons every time that new results of NFL games are available, so they can calculate not only the wide variety of wins, losses and ties that might occur, but also the variety of scores by which those games are decided.

For most of the season, these simulations have shown the Chiefs to have a double-digit chance to win the Super Bowl. Currently, FiveThirtyEight calculates the Chiefs have a 63 percent probability to make the conference championship, a 39 percent chance to reach the Super Bowl, and a 20 percent probability to win it.

Only the Saints — with a 21 percent chance — have a (slightly) better shot.