Betting Value: Finding the Bookmakers' Mistakes (EURO 2020 Quarter-Finals Day 1)

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The Art of Statistics (not to be confused with stats) at our service

A few days ago we re-published an article on the academic approach to modeling soccer games. Some of the global leaders in Sports Analytics have developed a statistical model that has been well-established since 2003.

If you are seriously interested in Football Analytics, we cannot stress how important it is to look at the aforementioned article. As professors of Statistics and founding members of the AUEB Sports Analytics Group they have great contribution to the field.

On Leonardo Egidi’s blog there is a section with EURO 2020 model predictions. The model he uses is an application of Karlis and Ntzoufras 2003 paper “Analysis of sports data by using bivariate Poisson models“. The model has been quite successful so far! In the Round of 16 it correctly saw that the Czechs had good chances against Netherlands, that Croatia and Spain would go to overtime, and that England would finally beat Germany.

Probabilities & Odds

Our attempt here is to find where bookmakers’ overvalue or undervalue an outcome. To do that, we compare the probabilities and odds of the bookmakers to those of the bivariate Poisson model.

Note that all odds below exclude the usual bookmakers’ vig, i.e. the profit they make. All probabilities add to 100%.

To convert from a probability to decimal odds, divide the probability by one. For example, in the probability table below, in the “Model Switzerland-Spain” row we see that Spain’s probability is 40%. The odds therefore are 1/0.4=2.50.

Vice versa, to convert from decimal odds to implied probabilities, we divide 1 by the odds. For example, odds of 2.50 give probabilities of 1/2.50=0.4 or 40%.

The bookmaker odds we have in the tables below are derived from around 20 UK bookmakers.

Switzerland vs Spain

Spain Win

The books give Spain 57% chances to win. Average odds: 1.75.
The model implies that the chances are 41%. In odds, this is 2.50.
Our experience says Spain is undoubtedly a very good team. In their last game, they finally did better than their xG (best in EURO) and scored 5 goals.
- They are great at creating chances and if they can continue converting them to goals Switzerland will suffer.
- Switzerland will capitalize on their great comeback against France and will use the momentum they built to unsettle their opponents. We expect them to defend better than they did against France, and Spain’s lower tempo might actually suit them. However, Spain is rightly the favorite and the odds reflect the betters’ beliefs.
- Nevertheless, we aren’t here to state the obvious, we are here to point out values!
Verdict: A bet on Spain is not worth it at the current prices. Something around 2.15 would be OK.

Spain-Switzerland Draw

The books give 26% chances of a draw. Average odds: 3.85.
The model implies that the chances are 25%. In odds, this is 4.00.
Our experience says The odds fairly represent the value of the draw. In our opinion, although the chances of a draw aren’t very high, knock-outs tend to favor close games. Spain had an excellent defensive record in the group stage and Switzerland has the mental preparedness to battle it out with their refuse to lose attitude. With both of the teams having drawn in their last game and a fair odd at hand, the draw certainly has value.
Verdict: A draw here has good value and is quite likely to happen.

Switzerland Win

The books give Switzerland 17% chances to win. Average odds: 5.88.
The model implies that the chances are 35%. In odds, this is 2.50.
Our experience says Switzerland is a much better team than what the betters think.
- We can see how much the betting companies and betters underestimate Switzerland as it is reflected in the average odds.
- Switzerland was prolific offensively but lacked defensively. However, even when everything seemed to have gone bad they showed faith in their attacking plan, fought until the last minute, and were rewarded.
- Don’t make the same mistake that the arrogant Deschamp’s side did. DO NOT UNDERESTIMATE SWITZERLAND!
Verdict: A bet on Switzerland has good value at the current prices. We get double the money on our chances.

Belgium vs Italy

Belgium Win

The books give Belgium 27% chances to win. Average odds: 3.70.
The model implies that the chances are 54%. In odds, this is 1.85.
Our experience says Belgium has great potential and they rightly aspire to reach the Final and win the EURO!
- They are a side that plays together for some years, they have had major setbacks in previous tournaments but this year they seem more mature than ever.
- For some of their best players, this is their last chance to win a major tournament, and they seem fired up fighting for every possession and even lost balls.
- Belgium performs great as a team and with Kevin De Bruyne being in such a great form this year, who would be surprised if they win against Italy?
- Before you bet on them though make sure that KDB will be in the line-up.
Verdict: A bet on Belgium is totally worth it at the current prices. We get double the money on the chances!

Belgium-Italy Draw

The books give 32% chances of a draw. Average odds: 3.12.
The model implies that the chances are 26%. In odds, this is 3.85.
Our experience says both teams are very capable of defending against good offensive sides.
- They have excellent players in central positions and strong defenders. So far they have played for the win, producing, at times, fluid creative attacking football.
- Is it possible that they neutralize each other’s weapons and head to overtime? It certainly is, and if you are willing to buy the chance of a draw the value of the average odds offered isn’t that unfair.
Verdict: A draw here has a fair value and is quite likely to happen.

Italy Win

The books give Italy 41% chances to win. Average odds: 2.44.
The model implies that the chances are 20%. In odds, this is 5.00.
Our experience says Italy has made a huge change in their playing style and tactical approach to games and it certainly pays off.
- They lack a super-star in forward positions like the ones they enjoyed the previous decades, but they still remain a powerhouse and the best defensive school of football out there.
- We’ve already analyzed how great their midfielders have performed, and although they weren’t that good in their last game they have what it takes to beat any national team in the world in our opinion.
- If it wasn’t for the severely under-priced odds we would have given it a thought but betting is all about value!
Verdict: A bet on Italy is not worth it at the current prices. We get half the money on our chances.