How Often Do Underdogs Win Outright?

Naturally there are different levels of underdogs and if you know me by now, you know that I will head to my computer and get all the details. There has been a lot of college football played since 1997, 15 years worth of it. If you count each FBS team playing a game (so 2 teams each game) in that span there were 20,882 different games of data for me to analyze.

Let’s look at the biggest favorites and you will see that Las Vegas does its job well picking out big favorites. Since 1997 there have been 596 teams that have been favored by OVER 31 points in a game. Of those 596 only SIX have lost the game straight up. The biggest upset ever was when Stanford (+41) upset USC in 2007 and showing what a weird year that was, the 2nd biggest upset ever was also in 2007 when Syracuse (+37) beat Louisville. The other 3 huge upsets since 1997 were: Temple (+35.5) over Virginia Tech in 1998, Central Michigan (+35.5) over Western Michigan in 2000, James Madison (+35) over Virginia Tech in 2010 and North Texas (+32) over Texas Tech in 1997. Basically if your team is installed as an underdog of 31 points or more in a game, they have a 1% chance of winning.

Now let’s look at the chances of your favorite team winning if they are installed as an underdog of 24.5 to 31 points. Since 1997 there have been 756 teams that have been favored by 24.5 to 31 points in a game. You would expect the underdogs would have a better chance of winning outright than the above teams and naturally they do. In that span 30 teams that have been favored by that margin have lost straight up in a game with three such upsets last year. Texas Tech was +28.5 when they upset Oklahoma on the road, Iowa St was +27.5 when they upset Oklahoma St at home and Sacramento St was +27.5 when they beat Oregon St on the road. The amount of upset did not go up as much as I thought they would as upsets occurred only 3.97% of the time or 1 out of every 25.2 games.

You would figure that the percentage of upsets in the 17.5 to 24 point favorites level would go up drastically from that 3.97% in the previous category. Since 1997 there have been 1,316 teams that have been favored by 17.5 to 24 points. I am still a little surprised that there were only 89 upsets in this level of favorites over the 15-year span. That is just 6.8% upsets which comes out to 1 upset loss for every 14.8 teams that are favored by 17.5 to 24 points. Last year there were six such upsets which included UNLV over Hawaii, Northwestern over Nebraska. Wyoming over San Diego St, New Mexico St over Minnesota, Colorado over Utah and UAB over Southern Miss.

http://philsteele.com/Blogs/2012/Aug12/DBAug1.html