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NFL Week 2 Elo Ratings And Playoff Odds

It’s a cliche: Every game counts in a league that plays just 16 of them. But Benjamin Morris’s findings in his debut Skeptical Football column were nevertheless striking: A Week 1 or Week 2 game can affect an NFL team’s chances of making the playoffs by as much as 20 or 30 percent.

We also see that reflected in FiveThirtyEight’s NFL Elo ratings playoff odds, a feature we debuted last week.

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What are Elo ratings? The short version: Elo ratings are a simple mathematical system originally designed to rate chess players. They’ve since been adapted to a number of sports such as soccer, and we’ve adapted them to the NFL. The Elo ratings only account for fairly basic information like wins and losses, strength of schedule and margin of victory. There are more advanced systems out there, but Elo ratings are transparent, easy to calculate and we can do a lot of fun stuff with them, like simulating the rest of the season and calculating playoff odds. For more on the methodology, see here.

In our Week 1 ratings — which were based on a team’s Elo rating at the end of last season — the New England Patriots had a 73 percent chance of making the playoffs and the Miami Dolphins had just a 32 percent chance. But the Dolphins upset the Patriots, and now it’s almost even: New England is at 54 percent to make the playoffs and Miami at 50 percent.

Why such a big shift? Well, every game counts (especially a divisional game; our simulation accounts for playoff tiebreakers). But also, the Patriots now look slightly worse than Elo originally pegged them, and the Dolphins look slightly better. Before Week 1, Miami had projected to win 7.7 games; it now projects to win 9.1. In other words, one NFL win for the Dolphins was worth more than one win in the Elo standings because Miami’s Elo rating improved.

Here are the latest Elo ratings and playoff odds for all 32 teams:

silver-elo-table-1-week2

A few other comments:

  • The teams with the largest gains on the week, in addition to the Dolphins, were the Minnesota Vikings, who gained 46 Elo points after demolishing the St. Louis Rams, and the Tennessee Titans, who added 38 Elo points after beating the Kansas City Chiefs. Both Minnesota and Tennessee are now better than even money to make the playoffs; the Titans are helped by playing in the league’s weakest division (although the NFC East might have something to say about that).
  • It’s early, but perhaps we’re seeing the emergence of a Big Three. The Seattle Seahawks are the most likely team to win the Super Bowl, at 16 percent, followed by the San Francisco 49ers at 13 percent and the Denver Broncos at 11 percent. Then there’s a fairly big drop to the Carolina Panthers at 7 percent.
  • Meanwhile, in the it’s-already-time-to-panic department, the Chiefs project to just a 6-10 record and have only a 13 percent chance of making the playoffs.

Elo ratings can also be used to derive point spreads. We strongly advise that you don’t bet on these, at least not without considering a lot of other information — Vegas betting lines are too sophisticated to be beaten by a simple system like Elo. Still, it’s fun to track their progress. Last week, they went 8-8 against point spreads as listed at Pro-Football-Reference.com.

silver-elo-table-2-week2

There are some funky matchups this week. Elo has the Vikings at almost even money at home against New England, while Vegas has the Patriots as 3-point favorites. Another point of disagreement is Seattle at San Diego; Vegas has the Seahawks as 6-point favorites — a lot on the road against a playoff team. Elo thinks they should be favored over the Chargers by a field goal instead.

Nate Silver is the founder and editor in chief of FiveThirtyEight.

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