Actual Wins: How many games a team actually won in a given year.
Decisive Wins: Wins by seven or more points.
Decisive Losses: Losses by seven or more points.
Close Games: A game within six or fewer points.
Average Wins: How many games a team won if you weight games as so:
Decisive Wins: 1
Close Games: .5
Decisive Losses: 0
Too many times, the narrative in football is that good teams win close games. This simply isn't true. By in large, if a team wins many more close games than they lose, the team isn't as good as its record. They got lucky. Records will lie to you.
A large majority of teams have a close game win percentage of roughly 50%. How large is the majority? Between 2008-2012 only 30 teams have had their Actual Wins within two wins of their "Average Win" total. That means 81.25% of teams over five years fit the narrative that close games are about 50/50 shots.
To go more in-depth with Average Win, I'm going to give an example:
Let's say the Houston Oilers start off the season like this:
Loss by 2
Loss by 4
Loss by 1
Loss by 1
Loss by 1
That leaves them with an actual record of 0-5, even though they only lost by a combined 10 points. Since I have found there is a value in close losses, I combined close wins and close losses, making them count as Close Games instead of Win/Loss like traditional win percentage.
Actual Win: 0
Actual Win: 0
Average Win: 2.5 (5 close games x .5)
Difference is simple, think of it as |Actual Win-Average Win|. It's the distance between Actual Win and Average Win.
If the Oilers kept this trend going, they'd qualify as one of the 18.75% of outliers which got either extremely lucky or unlucky by having a difference of two or more. Of the 26 teams between 2008-2011 (can't use 2012 data because I don't know their 2013 records), you will find a striking revelation.
Here are the "overrated teams" of 2008-2012. These are teams that won two or more games over their Average Wins. Only two teams (2008 Indianapolis Colts and 2010 New Orleans Saints) improved their record the next season. 2012 teams that qualified as "overrated" are the Indianapolis Colts, Houston Texans, and Atlanta Falcons.
Here are the "underrated teams" of 2008-2012. Only the 2011 Philadelphia Eagles had a worse record the year after they lost two or more games than their Average Wins suggested. The 2012 Carolina Panthers qualified for this list.
So, although it's a small sample size, only 3 of 26 teams that qualified for the overrated/underrated lists were incorrectly projected to improve/decline the next season. Out of those 3, 2 of them barely qualified with a difference of two. Only the Indianapolis Colts of 2008 disregard the narrative at all.
Why does this trend happen? Well, one reason is the penalties the NFL has against teams which perform well. If you win games, you get a lower draft pick, and you're scheduled against teams that finished in the same spot in their division in your same conference. If you were the 4th best team in the NFC South, but you ended up winning the conference, you play all the teams that won NFC conferences the next year. Already with an inflated record, you can't keep up with those good teams, leading to more losses.
If you are betting man, my advice would be to not bet on the Colts, Texans, or Falcons to improve, or the Panthers to decline, in 2013.