On Wednesday, Jason Lisk came up with a set of power rankings based on the point spread for nearly every game this season (spreads for the games in the final week of the season have not yet been released).
We can use the SRS to come up with the implied ratings for each team (this is what Lisk did, although I don’t think he used the SRS). So how do we come up with the SRS ratings? The point spread in each game provides an implied strength margin (“ISM”) between the two teams: When the Jaguars are 14-point underdogs in Denver, that implies that Denver is 11 points better than Jacksonville. If we treat each ISM like we would margin of victory, then we can use the SRS to come up with team ratings. For those who need a primer on what the SRS is, you can read about it here; the rest of you can skip to the ratings:
One interesting way to use the SRS is to see which teams have the hardest schedules. Pre-season strength of schedule is essentially meaningless when based on last year’s record, but the SOS ratings here are based on the perceived strengths of each team. In my opinion, you’d be hard-pressed to find a better set of strength of schedule ratings in May than what we see here (other than the fact that they exclude week 17).As always, the table is sortable, making it easy to see that the Vikings have the hardest schedule in the league. Only three of Minnesota’s opponents have negative SRS ratings, and frankly, I’m probably higher on all three of those teams (Carolina, Philadelphia, Cleveland) than most. Green Bay’s games against the Eagles and Browns are the only ones that come in below average in terms of opponent strength. Minnesota and Green Bay have much harder schedules than the rest of the league because they face the AFC North and NFC East, the other NFC North teams, and one each of Seattle/San Francisco and Atlanta/Carolina (while the Vikings escape Atlanta, their schedule is harder than the Packers because they have to face Green Bay twice and the Packers final game is at Chicago (while Minnesota’s last game is home for Detroit)).
Meanwhile, the teams in the AFC West and AFC South have very easy schedules: that’s because they play each other. Ten of the Jaguars opponents are below-average this year, although the other five are Denver, Seattle, San Francisco, and two games against the Texans. Jacksonville’s 16th game is against the Colts, who — despite Andrew Luck, the 11-win season from last year, and the Irsay/Grigson campaign to sign every mediocre free agent out there — are graded as 1.2 points below average.
The table below shows each game in the first sixteen weeks of the 2013 season and some useful information. For example, here’s what the Broncos/Jaguars line says: In week 6, Denver hosts Jacksonville. The line is -14, which means the Broncos are 14-point favorites. Denver’s SRS is 4.5 while the Jacksonville’s SRS is -6.3. Therefore, the line predicted by the SRS would be Denver -13.8 (since the Jags are 10.8 points worse than the Broncos and on the road). The difference between the actual line and the SRS line is -0.2 points. By definition, the sum of all the differences between the actual lines and SRS lines must be 0, since the SRS lines were generated from the actual lines.
- We can sort the table by the “difference” column to see some outlier games. The biggest outlier games are in weeks 1; as Lisk noted, the lines build in some risk of injury (or simply risk of not knowing what’s going to happen in the future): if Tom Brady or Peyton Manning miss time with an injury, it’s more likely to be later in the season than in week one. Additionally, if Vegas feels more confident in the early games than the late games, that will lead to some games appearing as outliers in week 1.
- The Chargers (SRS of -1) host Houston (+1.4) in week 1; we would expect from those ratings that San Diego would be 0.6-point favorites. Instead, the Chargers are 3-point underdogs. Similarly, the Jets are projected as just 0.9 points worse than the Bucs. At home in week 1, we would expect New York to be 2.1-point favorites; instead, Darrelle Revis and the Bucs are 1.5-point favorites.
- Two weeks later, the Chargers travel to Tennessee. San Diego (-1) should be a slight favorite over the Titans (-4.2), but in fact are 2.5-point favorites. That’s even weirder when you consider that it’s a 1PM game; if anything, you might expect Tennessee to be a 1-point favorite.