There seems to be a growing belief that if you’re going to bet on an underdog in the NFL, you should bet them on the money line. Of course, like many growing beliefs, this one is rooted in very recent evidence; over the past 3 weeks, 23 of the 27 NFL underdogs that have covered the spread have also won outright (85% win rate). So let’s all bet underdogs on the money line, right? Well, not so fast.
If you look at the entire 2011 NFL season, the percentage of underdogs that covered the spread and have also won outright drops to 69.8% (lower than the 85% win rate of the past few weeks). But if you look back over the past 23 years, the percentage of underdogs that covered that also won outright drops even further – to 66.2%.
Let’s get even more granular in this analysis because not all underdogs are created equal.
- Underdogs getting between 1 and 3 points are 937–896-108 against the spread (ATS). Of those 937 underdogs that covered, 863 won outright – a 92% win rate.
- Underdogs getting between 3.5 and 6.5 points are 968-955-22 ATS. Of those 968 underdogs that covered, 641 won outright – a 66.2% win rate.
- Underdogs getting between 7 and 10 points are 701-646-36 ATS. Of those 701 underdogs that covered, 364 won outright – a 51.9% win rate.
- Underdogs getting between 10 and 14 points are 359-300-15 ATS. Of those 359 underdogs that covered, 136 won outright - a 38.2% win rate.
- Underdogs getting more than 14 points are 61-53-2 ATS. Of those 61 underdogs that covered, 6 won outright – a 9.8% win rate.
So when considering whether to bet your underdog on the money line, consider the point spread of the game and the historic win rate of teams in that spread range. If, for instance, you like an 8 point underdog and the money line offers you better than +200, there’s likely value in betting that dog on the money line (since they win at a 51.9% rate). But if a 15 point dog offers a money line of +600, you’re better off taking the points (since dogs of that size only win outright 9.8% of the time).
Remember, don’t fall victim to the all-too-common recency bias and consider the long-term perspective when attempting to play trends.