Going into the 2015 AFC Divisional Round, few sportsbookers gave the Indianapolis Colts much of a shot against the Denver Broncos; in fact, OddShark.com offered a computer prediction of Denver 31.8 to Indianapolis 28.4 and reported the Colts as a seven-point underdog. The Broncos – entering the game – were the AFC’s only undefeated team at home and only team in the NFL that had both a top five offense and defense. Despite having nine Pro Bowlers on their roster, the Broncos were unable to shake off Quarterback Peyton Manning’s 26 of 46 completions, which led to a lopsided 24–13 upset victory for the Colts.
This matchup illustrates the difficulty in accurately handicapping underdogs in the NFL. According to papers published by Richard Borghesi and Steven Levitt, the sports booking bias against home underdogs has historically produced a winning record that far exceeds the spread. For example, from 1942 to 2012, regular season teams that were favored by six or more points – but no more than 11.5 points – had a winning record of 1,361-1,475-57 (.480), while teams favored from .5 point to 5.5 points had a record of 2,197-2,330-156 (.485). From 2005 to 2012, teams favored by 12 or more points won 64-94-2.
This unpredictability not only makes the NFL impossible to analyze with statistics alone but allows those willing to go against popular opinion ample room to profit. Professional football is a game played by heart – one that allows those contrary to the spread ample opportunity to beat the odds.
Games Played as the Underdog
There are few teams that have successfully avoided being an occasional underdog. Typically, teams that were “top dogs” one season can find themselves underdogs the next season due to player and management changes. The league’s prevailing “top dog” team, the New England Patriots, found themselves underdogs in the 2014 AFC Championship against Denver. In 2015, the Patriots had the spread against the Colts for the AFC title match.
Games Won as Underdog
Despite most NFL teams spending more than half of their regular schedule as the underdog, they manage to contradict the spread by winning 35 percent of the time. This reflects the fact that many sportsbooks would set spreads contradictory to popular thinking to maximize betting opportunities. This also illustrates the fact that players’ conditions, field conditions, the officials assigned to a game, and other variables all present dynamic factors impossible for the sportsbook to accurately predict.
Winning Percentage as Underdog
Contrary to logic, the teams that have the best typical performance as an underdog are not necessarily the teams with the best winning records. The all-time win leader – the Denver Broncos, with a winning record of 504-366-14 and a winning percentage of .590 – for example, is sixth in winning percentage as an underdog. The Dallas Cowboys – second in all-time wins at 434-314-0 (.580) – is 14th in underdog wins. Conversely, the Steelers – 17th in the winning records at 534-510-21 (.511) – is second in most wins as an underdog.
The Most Overpowering and Overmatched Teams
Typically, teams that are unlikely underdog candidates are also most likely to be considered overmatched when playing as an underdog. It may be that these teams have less experience playing from behind, but when the spread tends to be against the “usual suspects” list of megawatts teams, odds are good that these teams will lose. Likewise, teams that are more likely to be underdogs tend to perform well in that light. These are good teams to go against the line with.
Most Lopsided Games
Many might feel that their luck may strike betting against the spread on a large odds game. Statistically, however, that’s unlikely; it’s unusual for games with large money odds to go against the spread. Such large odds suggest that there is something obvious – such as the team’s demonstrated lack of a passing game or a major injury – that is leading the sportsbooks to be comfortable offering such lopsided odds. It’s more likely for an underdog to come up on top of games with smaller odds.
Biggest Upsets – AFC Teams
Biggest Upsets – NFC Teams
Despite logic, football is a game that sees miracles happen on a regular basis. Legendary coach Vince Lombardi once said, “It is essential to understand that battles are primarily won in the hearts of men.” Football goes beyond statistics; it’s a game of passion. As such, shrewd bettors or astute students of human behavior can easily exploit the spread to make it work for them.
We took the closing NFL odds for every season between 2006 and 2014 on footballlocks.com and combined each with the game results from pro-football-reference.com to see how every NFL team performed when listed as the underdog.
The most overpowering teams were determined by averaging the money odds for every team when they were the favorite. The lower the number, the more the odds favored them. The most overmatched teams were determined by averaging the money odds for every team when they were the underdog and the higher the number, the more the money odds favored their opponent.
The most lopsided games were determined by finding the games with the highest difference between the money odds for the favorite and the money odds for the underdog.
The biggest upset victory and loss for each team were determined by looking at the highest money odds game for which the team was the underdog and won and for which they were the favorite and lost.