Why is a 70% Win Rate Unrealistic When Betting on the NFL?
The sports betting industry is one that lacks regulation, meaning anyone can start a company, website or used car salesman persona to start selling picks. Because there is no regulation, handicappers can tout false records and promises of unimaginable wealth in order to obtain business.
While there are many legitimate and transparent handicappers in the industry, there are also an overwhelming amount who use fake names, flashy cars, women of questionable clothing and morals (we’re guessing) and unachievable records to convince new or uneducated bettors to buy their picks.
While this may sound a bit over the top, we often get calls asking why we don’t hit 70% of our games like many of the other services out there. Our response is always that a 70% win rate isn’t attainable over the long-haul.
To explain this in more detail, we analyzed the probability that a sports bettor can win 70% of all wagers to illustrate just how unrealistic this is.
For the purposes of this article, we chose the z-ratio (also known as z-score) to show how many standard deviations away from “expected” an event is.
Example 1: No Edge
This example assumes a handicapper who historically hits 50% of his games, meaning the handicapper does not have any edge when picking games. The data assumes 1,000 plays against the spread (with a vig of -110) over a calendar year, across all major US sports.
|Desired Win Rate||Odds of Win Rate||Probability of Win Rate||Z-Ratio|
|50.0%||1 in 2||50%||0.0|
|51.6%||1 in 6.3||15.9%||1.0|
|53.2%||1 in 44||2.3%||2.0|
|54.8%||1 in 700||0.1%||3.0|
|70.0%||< 1 in a trillion||< .0000000001%||> 10.0|
As you can see, a sports bettor with no edge has only a 2.3% chance of winning 53.2% of his games, which is just above the break-even point of 52.4%.
That same bettor has less than a one in a trillion chance of hitting 70% of his games over the course of 1,000 plays.
Example 2: Good Handicapper
We ran the same analysis above but this time assumed a skilled handicapper who historically hits 55% of his games. The data assumes 1,000 plays against the spread over a calendar year, across all major US sports.
For the record, we do believe there are good handicappers out there that are able to achieve 55% over the long-term, which is a very good win rate.
However, even in the case of a handicapper with a long-term expected winning percentage of 55%, a 70% win rate over a whole season (with 1,000 plays) would still be a hugely unexpected event.
In fact, this is still an almost-impossible “9 standard deviation event” with the odds of a 70% or better win rate occurring less than one in a billion (.0000001%).