One of the most popular sports betting systems is the “contrarian method” of going against whatever side the public is backing. The idea behind this betting system is that the public can. Betting a Favorite: The odds for favorites will have a minus (-) sign, and represent the money you need to risk to win $100. So if you're betting on the Packers at -140 against the Vikings, that means Green Bay is a slight favorite. You need to risk $140 to win $100 on the Packers. If they win, you profit $100 and get your original $140 back. Find NFL odds, point spreads, and betting lines for the 2020-2021 football season. Visit FOXSports.com for this week's top action! When betting the spread, the odds for both teams are often -110. This means a bettor has to wager $110 to win $100. Therefore, if the money is evenly split, the bookmakers simply pay winners from the money collected from losers and pocket the remaining 10%. Let’s use the matchup of Kansas City at New England (-7.5) as an example.

• How To Read Betting Odds
• Top 10 Online Betting Sites
• Betting Against The Odds Meaning
• Betting Against The Odds

Easily the most popular type of betting for NFL football is “spread” betting or more commonly known as betting against the spread. Bettors who are new to NFL betting or betting in general may be a little confused with NFL spread betting, but it is pretty easy to understand once it is explained to you. We will explain what betting against the spread means below.

What is Betting Against The Spread?

For each NFL game the oddsmakers set a number of points in which the favored team is favored by. Bettors can then either choose for the favored team to win by more than the number of points set, or bet on the underdogs to lose by less than the number of points they are underdogs by or win the game straight up. For example, the spread could be set on the favored team at 6.5 points. This would mean in order for a bet on the favored team on the spread to win they would need to win by more than 6.5 points (7 or more) in order to win the bet. It also means that a bet on the underdog team would win if the underdogs lost by less than 6.5 points (6 or less) or won the game outright.

Example of NFL Spread Bet

Below is an example of what NFL spread betting would look like:

Matchup

• TeamsSpread
• Dallas Cowboys -2.5
• New York Giants +2-5

The negative (-) sign indicates that the Cowboys are the favorites, while the positive (+) sign indicates that the New York Giants are the underdogs. With the spread set at 2.5 points, a bet on the Cowboys would mean that they would have to win by more than 2.5 points (3 or more) in order for you to win that bet. A bet on New York would mean that the Giants would have to either lose by 2.5 or less points (2 or less) or win the game outright in order for your bet to win.

Here is another example with a screenshot taken from 5Dimes.eu during Week 3 of the 2013 NFL season:

Here you can see that the Rams are +3.5, while the Cowboys are -3.5. So for this example the Cowboys are 3.5 point favorites, while the Rams are underdogs of 3.5 points. If you were to bet on St Louis you would need them to lose by 3 or fewer points or just win the game outright. If you were to bet on Dallas you would need the Cowboys to win by 4 or more points.

If the Cowboys were to win by 3 points, lets say 30-27, any bets on the Rams +3.5 would win. Even though the Rams didn’t win the game they covered the spread of 3.5 points.

Now if the Cowboys were to win by 4 points, lets say 31-27, the Cowboys have covered the spread and anyone who wagered on Dallas would win their bets.

Other NFL Spread Betting Information

You may often notice that the spread is sometimes set at an even number such as 3, 6 , 10, etc. In this case if the favored team won by the exact amount set for the spread the bet would be pushed, and all bets would be returned. For example, if the Patriots were 3 point favorites and they won by a FG (3 points) than this would results in a push, meaning no matter which side you bet on you would get your money returned to you.

The most common NFL spreads are usually set between about 2.5-10.5 points, but you will also almost always have games each week with spreads lower than 2.5 and higher than 10.5. In the event that the oddsmakers feel the game doesn’t need a spread, it would be set at 0 or what some call a pick’em (both teams are given even odds to win for this type of bet).

The odds given on the spread are usually -110 unless otherwise noted. It is not uncommon to see one side of the spread being -105, with the other side being -115. If you don’t see any odds listed for each side of NFL spreads you are supposed to assume the odds are -110 on each. Not sure how to read NFL betting odds? Check out our Sports Betting Odds guide.

Now that you know the basics of NFL spread betting you’ll want to check out our Sports Betting Strategy guide which has some great NFL strategy articles written by a professional bettor.

My First Foray Into Gambling

I started betting on football (soccer) during high school. After school I would head to the bookies with a few friends to check out the odds section in the newspaper. We would test different strategies wagering no more than $1 or $2 at a time. We lost often, but also won big on rare occasions due to parlay plays. I remember a friend winning almost $250 once, a real fortune at the time. I had also heard stories of others winning a few thousand betting only a few bucks. Good times!

You could find interesting characters hanging at the bookies then. You had to actually show up, or phone-in your bet, because there were no apps or smartphones. And they had all sorts of schemes. Some would only bet on the favorite claiming a sure thing, others on the long-shots claiming they were undervalued, and others yet on the number of goals in the first 30 minutes according to some foolproof system.

As far as I can remember they were all unemployed and poor. But together we gambled . I tried to multiply my lunch money and they tried to multiply their social pensions.

After months of losing, I stumbled upon what would become my go-to strategy. Instead of betting on a team, I started betting on neither. Specifically, I would bet on the number of goals in a particular game: 0 to 2, 2 to 3, or +3. I noticed that at my bookies these bets were all priced with a 1.6 or 1.9 coefficient. That meant that a $1 bet would pay $1.6 or $1.9 respectively.

I also noticed that these odds were offered the same across all leagues, yet all leagues were different. At the time (circa 2007) Barcelona and Real Madrid would win matches with 4 goals, while Italian teams would defend their 1-0 advantages to death. Clearly this was an opportunity in my eyes.

Betting on few goals in the Italian Serie A and many goals in La Liga and the Premier League proved to be a good strategy, winning me consistent lunch money. After some time I became a respected regular at the bookies and many inquired about my opinion on bets. All this “fame and fortune” eventually got to my head, and I ended up losing it all (a few hundred bucks) on the 2008 European Cup.

The Biased Odds

The experience of losing it all in a matter of weeks has always haunted me, not because of the money but for the manner in which it happened. This sparked an internal fire to find a foolproof system, a method that beats the bookies in a quantitative way.

My first idea was to beat the bookies with a better model. Bookies have an accuracy rate of roughly 55% (in EPL) in favoring the winner in a particular match. I thought I could get to at least 60% accuracy with my incredible modeling skills. Soon I realized the futility of this endeavor (see my article here).

Regardless of the complexity of the model you choose – and I used many ranging from simple linear regressions, multivariable regressions, local regressions, regularized regressions, logistic regressions, random forests, boosted trees, etc, etc. – the quality of data is king. (I’ve yet to try Poisson simulations though…)

In the article I linked above I describe the data I have available. It is a massive dataset with matches since the early 2000s from all the major leagues. It contains results, shots on goal, corners, cards, fouls and bookies’ odds. But it is not enough. Unfortunately, after a lot of time spent thinking about this problem, I am now convinced that in order to beat the bookmakers you need to have data at least as good as theirs. This should include at least: team composition (i.e. strength of the players in the lineup), injuries if any, possession data, and other gameplay style statistics.

After giving up on the idea that I could come up with a better model, I chose to look at the offered odds and see if anything “stuck out.” I should preface this that before looking I had noticed that bookmakers (Bet365 specifically) had never predicted a draw in the Premier League since 2005. Not a single one! And yet almost 25% of EPL games ended in a draw. In fact, I had tried several models to predict draws, all of which performed no better than a random guess.

I decided to plot the percentage of home team wins, losses, draws vs. the probabilities of a home win ascribed by the bookmaker.

On the top chart, percentage of actual home team wins is plotted against the probabilities of the home team win derived from the bookmaker odds.

The middle chart contains away team wins, while the bottom chart has draws. Again the x-axis is the given probability of a home team win.

So looking at the top chart, the red dashed line crosses 30% both on x- and y-axis. The data points touch the dashed lines perfectly. This means that when the bookies ascribe a 30% probability of a home win, the home team indeed wins about 30% of the time.

The odds offered to the gamblers are slightly worse than 30% however. In order to arrive at 30%, “the spread” should be removed from the given odds. I’ve described the process how to arrive at probabilities in the linked article.

How To Read Betting Odds

The middle chart shows that there is roughly a 40% probability of an away win when the bookmaker offers 30% home win probability. This makes sense because the bookmaker is favoring the away team to win. Remember that Bet365 never favors draws. Hence, it is ascribing about 40% to the away team win, which is close to the true percentage (This is observable by plotting the same charts but with the x-axis representing the ascribed probability to an away win.)

30% for the home team + 40% for the away team = 70%. This leaves a 30% probability ascribed to the draw (roughly).

However, the bottom chart displays an interesting pattern. When a 30% probability is given to the home team (hence about 30% to for a draw as well), the matches end in draws over 35% of the time (mostly)! The green circle contains the games ending in a draw over 35% of the time while the red circle the ones under 30% . Averaging these together would be closer to 35% since there are more cases of draws there. The same pattern is observable if the home wins’ probabilities were replaced by away wins’ ascribed probabilities.

Top 10 Online Betting Sites

Simply put, this means that Bet365 underestimates the likelihood of draws consistently when the teams are equally matched. This coincides with matches having 30% to 35% probability ascribed to the home team. Of these games, up to 40% of them end up in a draw. Yet, Bet365 never offers draws as the favorite result, opening up a potential opportunity for profit.

I have no idea why they do this. I think it is likely because EPL punters do not like to bet on draws and hence Bet365 needs to offer better odds to entice them. Or maybe because fewer EPL games end in a draw compared to other leagues. This is just my speculation.

A Systematic Model

Betting Against The Odds Meaning

After observing this pattern I started thinking about methods to exploit it. The most logical one (to me) and simplest was to devise some filter for matches with equally-matched teams. I did this by computing the difference between the bookmaker’s ascribed home and away probabilities to see if there was a threshold that had a higher percentage of draws. For example, if the home team was given 40% probability of a win and the away team was given 30%, the difference would be 10%.

I ran several benchmarks of EPL historical matches since the 2005 season with thresholds ranging from 5% difference to 15% and found that the optimum is somewhere in-between. Under 12% but over 10%. It turns out that betting on draws in matches where this difference is 10% or less if quite a profitable strategy, returning roughly 33% a year.

Starting with $1,000 in the 2005 season would yield almost $9,000 in profit today. However, the strategy is not foolproof, with many seasons having significant drawdowns, but overall it has positive expectation. Additionally, it does appear that Bet365 could have potentially caught on given that since 2018 the strategy has broken even. It is has not been a loser though!

Moving the threshold around is a balancing act between accuracy and volume. The higher the threshold the more games pass the filter, but fewer of them end up in a draw. 10% difference between home and away seems to be the sweet spot.

Betting Against The Odds

I ran a t-test on the Profit and Loss time series to see if the positive return was statistically significant. The test returned a t-statistic of 1.74, which has a p-value of 0.08. This means that it is significant at the 90% percentile, albeit not at the more widely used 95% percentile. Still, I would regard this as a very positive result. The signal is not infallible, but it certainly is there.

Having come up with a positive result, I tested the same method in other leagues. Unfortunately, it worked in none of them. I say unfortunately because I kind of wish it would, but in fact, it is good news that it does not. These biases in the odds are hard to come by and if they were prevalent in many games someone would have caught on (if they haven’t already).

Why Post This?

I want to be frank and disclose that I would never post a profitable strategy that would make me money. I would be crazy if I did that!

The reason I am putting this out is because I cannot take advantage of it in the real world due to soccer betting being illegal in my state. I hope your government is less stringent however. And if you ever feel like betting on soccer, try this system out.