Monday, August 19, 2013

2013 NFL Strength of Schedule Power Ratings

In addition to overall NFL power ratings, I also created strength of schedule (SOS) power ratings during the summer. I used a simple formula based primarily on season win totals for the 2013 season in order to comprise these rankings. This activity helps identify teams getting respect from oddsmakers despite having a difficult schedule, as well as add perspective to the season win numbers. For example, San Francisco and Seattle have almost identical win totals, but the 49ers play a tougher schedule by a decent margin according to our ratings. This would suggest that San Francisco is the better team, but the same conclusion could not be drawn by simply considering raw season win numbers.

I've always preferred to use season win totals from reputable sportsbooks to forecast strength of schedule for the upcoming season. Not only do NFL teams naturally regress/progress from year to year, but other transactions take place during the off-season that can either ameliorate or worsen a roster. Indianapolis won eleven games last season, but after digging through their advanced metrics, the Colts appear to be more like an eight-win team in retrospect. Last year's success was somewhat of an anomaly for Indianapolis and it would be unrealistic to expect them to win eleven games again this season.

I used the season win totals posted on Bookmaker (part of the CRIS family) to construct SOS power ratings for each team. The shop is offering $5,000 limits on these propositions which leads me to believe they have confidence in their numbers.

The formula to create an NFL schedule consists of six games between divisional opponents, eight games against two different divisions, and two games vs. two different teams based on win/loss record from the previous year (sometimes referred to as "field games").

For example, the two divisions Minnesota will play are the NFC East and the AFC North. They also have to face Chicago, Detroit and Green Bay two times each because they are all in the same division. In this scenario, Minnesota will play Carolina (2nd place in NFC South) and Seattle (2nd place in NFC West) in their two field games because each team finished second in their respective divisions last year. I simply added up the season win total expectations for all 16 of Minnesota's opponents and arrived at a strength of schedule power rating of 137.80.

I added the numbers up using the aforementioned formula for each individual team and these are the results I came up with.

       Team            SOS Rating
1 Minnesota              137.80 
2 Arizona                  136.75
3 St. Louis                 135.40
4 Washington           135.10
5 Tampa Bay            134.25
6 Baltimore               134.15
7 Carolina                 133.85
8 Atlanta                   133.60
9 New Orleans         132.90
10 Green Bay           132.65
11 Chicago                132.05
12 New York (G)     131.90
13 Dallas                   130.65
14 Detroit                 130.35
T-15 San Francisco  130.10
T-15 Oakland           130.10               Average: 130.06
17 Cleveland             129.95               Median:  130.03
18 Philadelphia         129.65
19 Buffalo                 128.95
20 Cincinnati            128.65
21 New England       128.45
22 Miami                  128.25
23 New York (J)      128.10
24 Tennessee            128.00
25 Jacksonville         127.75
26 Seattle                  127.45
27 San Diego            127.05
28 Indianapolis        125.45
29 Houston              125.00
30 Pittsburgh           123.20
31 Kansas City         122.75
32 Denver                121.80

Here is a breakdown of the division matchups:

NFC East:    NFC North and AFC West 
NFC North: NFC East and AFC North       
NFC South: AFC East and NFC West        
NFC West:  AFC South and NFC South

AFC East:    NFC South and AFC North  
AFC North: NFC North and AFC East
AFC South: AFC West and NFC West
AFC West:  AFC South and NFC East