NFL Season Win Totals: The Strength of Schedule Index
August 09, 2007
NFL schedule strength can change considerably from year-to-year. A crucial factor in analyzing Team Season Win propositions is comparing last year's sked to this year's, looking for teams taking a big step up or down in degree of difficulty.
The Parity League
Unlike other major sports, the NFL schedule maker has a fair amount of wiggle room; only 10 of 16 regular season games are pre-determined. These are the 6 divisional games and 4 interconference games (playing each division from the opposing conference once every 4 years). The remaining 6 games are typically used to add parity. Teams coming off good years will usually play other good teams from their conference in these "discretionary" games, while poor teams will be matched against one another. This is one reason favoring high win or high loss teams returning towards .500 the following year. Which teams might be helped or hurt by this year's schedule?
Schedule Change Index
In order to create this index, I have analyzed both last year's and this year's schedules for each of the 32 teams.
1. To get last year's strength of schedule I tabulated the total number of wins for each team's 16 opponents in 2006.
2. This year's strength of schedule is a two step process. First, I took the 2006 wins for their 2007 opponents. In order to adjust for off-season changes, I also added up the opening season win totals lines for their 2007 opponents. We then average the two totals.
3. Lastly, we rank both 1. and 2. from 1 to 32, take the difference and then rank that.
In this way, the #1 team is the one who's schedule has got the most easier compared to last year while #32 has seen the most increase in difficulty. I am looking to bet on teams with bad records from last year that score high or to bet against good teams that score low. Here is the alphabetical listing of the "Schedule Change Index":
Putting it all Together
The 4-win Buccaneers score #1 on this index; they go from last year's 5th toughest sked to this year's 3rd easiest. Meanwhile, the 13-win Ravens are #32 with the 5th hardest sked after last year's 25th.
A key of this index is that it only highlights changes between years, rather than a single year. The 13-win Bears had last year's easiest schedule, but do so again and only rank #15. Tied with them are the hard up Bills who come off last year's #1 difficult sked with a repeat of the same.
Before pulling the trigger on a season win bet take a long look at strength of schedule. Last year there was a 60% correlation between it and season win-loss record. To see a small spreadsheet with the full data click here.
Reed Hogben M.D.