quantitative analysis in football (soccer)

Since 2014 I have developed a strong interest in the quantitative analysis of sports, especially soccer; Top tier newspapers, such as The New York Times, The Times, Le Monde and El País, have published my articles on the FIFA World Cup, FIFA rankings, the UEFA Champions League, the UEFA Euro 2016, domestic leagues, and competition formats in general. My main research interest here is fairness in sports, in particular the fairness and efficiency of competition formats, ranking systems, seeding systems, draw procedures, and match schedules. Round of 16 of the 2021-22 UEFA Champions League: Should the whole draw have been canceled? Several bugs occurred during the draw of the round of 16 of the 2021-22 UEFA Champions League which took place on December 13, 2021. I analyze those bugs from a probabilistic point of view and explains where the re-draw should have started, instead of the whole first draw being canceled. This is explained in the following article: - Ligue des champions : fallait-il annuler complètement le résultat du premier tirage ?, Le Monde, December 14, 2021 (in French). Available online here. A better format for the 2026 FIFA World Cup The United States, Mexico, and Canada will host the twenty-third FIFA World Cup in 2026. In January 2017, FIFA announced that for the first time, the tournament will feature 48 teams, a 50% increase compared to the current 32-team format, and that the group stage would consist of 16 groups of three. Each group would play a traditional round-robin and the best two teams in each group would advance to the knockout stage, which would start with the round of 32. Using groups of three is a bad idea for many reasons: high risk of collusion; imbalanced schedule; teams can be eliminated after only two games; unnecessary idle time for all teams during the group stage; loss of sporting and financial value for FIFA and the host countries. Luckily, there are better ways to organize a 48-team World Cup, and FIFA still has plenty of time to switch to a better, fairer, and more efficient format. I suggest a format with 8 groups of 6. For the tournament to still fit in one month, within each group teams would only face 3 opponents. To this end, each group would be split into 2 cross-competing subgroups of 3. A system of 6 pots of 8 teams could be used during the draw to guarantee that the subgroups are well balanced. Compared to 16 groups of 3, this format would drastically reduce the risk of collusion, offer a minimum of 3 matches to all teams, have a regular match schedule, and increase revenue for FIFA and the host countries (more games, no more idle time for teams during the group stage). I also suggest a calendar and bracket. They prove that, with 6 matches per day scheduled during the group stage, the tournament would still fit in one month (for example, June 10 to July 12, 2026), while teams would still be guaranteed 3 full rest days between 2 matches. I believe 18 stadiums would do the job (2 full rest days for each stadium between 2 games). This is explained in the following article: - Football : "La FIFA doit revoir le format de la Coupe du monde 2026", Le Monde, November 19, 2021 (in French). Available online here. Coronavirus crisis: How to decide the final standings of a domestic league? Due to the coronavirus crisis, all European domestic leagues have been suspended. How to decide the final rankings if the season cannot resume? I have suggested a simple method which takes into account the strength of the opponents left to be played and the number of remaining home and away games. If we simply take the current standings (March 15, 2020) as the final standings, the teams that have had a more difficult schedule so far (more away games, stronger opponents) are aggrieved. If we take the standings at half-season (every team has played each opponent exactly once), we discard useful information (all the games played since half-season), and a team may still have benefited from the home/away schedule, winning at home against strong clubs and winning away against weaker teams, for example. My method estimates the number of points that the teams would have won on average in the rest of the season, based on the results of the domestic league so far. However, it is not a predictive model. The model is only used to make the slight adjustments to the current rankings that are needed to reflect the strength of the remaining opponents and the number of home/away games. It is, on purpose, very simple: the objective is that it can be put into future domestic league regulations, as opposed to more sophisticated predictive models that take into account recent form, injuries, results from past seasons, etc., elements that cannot be put in written regulations. It only uses the current standings (number of points) and the famous logistic regression (this is the same formula as for Elo ratings, a formula which is already used by FIFA for the national teams rankings, so domestic leagues should not be afraid). The main benefits of my method are the following: (1) it takes all the results of the current season of the domestic league into account (as opposed to only the first half of the season), (2) only the results of the current season of the domestic league are taken into account, so the rankings are not influenced by older results or by results of other competitions, and (3) it offers a simple, robust, scientific way of adjusting the current rankings to decide fair final standings. UEFA may want to encourage all European domestic leagues to include this method (or a similar one) in future regulations; indeed, a common European-wide rule seems preferable to each league cooking its own provisions. This is explained in the following articles: - The model to determine Premier League standings, The Times, March 18, 2020. Available online here. - Football : comment décider du classement final de la Ligue 1 si elle devait s'arrêter ici ?, Le Monde, March 16, 2020 (in French). Available online here. 'Choose Your Opponent': A New Knockout Format for Sports Tournaments I have suggested a new knockout format for sports tournaments, that I call "choose your opponent", where the teams that have performed best during a preliminary group stage can choose their opponents during the subsequent knockout stage. The main benefit of this format is that it makes the group stage more exciting, by giving teams a strong incentive to perform at their best level. It also makes the group stage more fair, by limiting the risk of collusion, canceling the risk of tanking, and making sure that the best group winners are fairly rewarded. Advancing teams would choose their opponent during new, much anticipated TV shows which would attract a lot of media attention. I illustrate how this new format would work for the round of 16 of the UEFA Champions League, the most popular soccer club competition in the world. This format can also be adapted to maximize some objective. For instance, I show how it could have been used to maximize the number of home games during the knockout stage of the UEFA Euro 2020, the first edition of the soccer European championship to be hosted by 12 countries. This is explained in the following articles: - Champions League knockout draw: What if group winners could choose their opponents?, Four Four Two, December 11, 2020. Available online here. - Ligue des champions : et si les vainqueurs de groupe choisissaient leur adversaire pour les huitièmes de finale ?, Le Monde, December 17, 2019 (in French). Available online here. - 'Choose Your Opponent': A New Knockout Design for Hybrid Tournaments, Journal of Sports Analytics, vol. Pre-press, no. Pre-press, pp. 1-21, 2021. Available here. Preprint available here. - 'Choose Your Opponent': A New Knockout Format for Sports Tournaments. Application to the Round of 16 of the UEFA Champions League and to Maximizing the Number of Home Games During the UEFA Euro 2020, SSRN, November 2019. Available online here. Risk of collusion: Will groups of 3 ruin the FIFA World Cup? In 2026, for the first time, the FIFA World Cup will gather 48 men's national teams. It will consist of a group stage made of 16 groups of 3, with the best 2 teams in each group advancing to the knockout stage. Using groups of 3 raises several fairness issues, including risk of match fixing and schedule imbalance. However the main danger is the risk of collusion. The two teams who play the last game in the group know exactly what result will let them advance to the knockout stage. Suspicion of match fixing occurs when a result qualifies both of them at the expense of the third team of the group, and can seriously damage the tournament. I have quantified how often this is expected to happen and explained how to build the match schedule so as to minimize the risk of collusion. I have also shown that forbidding draws during the group stage (a rule considered by FIFA) does not eliminate the risk of match fixing. This is explained in the following articles: - Why Groups of 3 Will Ruin the World Cup (So Enjoy This One), The New York Times, June 11, 2018. Available online here. - FIFA, We Fixed Your World Cup Collusion Problem for You, The New York Times, June 26, 2018 (with Toni Monkovic). Available online here. - Risk of Collusion: Will Groups of 3 Ruin the FIFA World Cup?, Journal of Sports Analytics 6(4):259-279, 2020. Available online here (free access) or here. What a fairer 24 team UEFA Euro could look like For the first time in 2016, the UEFA Euro gathered 24 men's national teams. Since the 24 teams are divided into 6 groups of 4, it is not straightforward to build a fair format for the knockout stage. I have critically examined a number of flaws in the current knockout bracket of the UEFA Euro 2016 and I have suggested two fairer procedures that eliminate group advantage and lack of win incentive and still satisfy the balance and group constraints. The suggested procedures apply to any tournament consisting of a round robin stage made of 6 groups of 4, followed by a knockout stage. The new formats that I suggest for a fairer 24-team UEFA Euro are described in the following articles. UEFA has adopted one of the new structures for the final bracket that I suggested (Structure 6 in the first article below) for the UEFA Euro 2020. Group advantage will be more fairly distributed among groups! - What a fairer 24 team UEFA Euro could look like, Journal of Sports Analytics, forthcoming, 2018. Available online here. Preprint available online here. - Euro 2016 : comment le tableau final favorise la France, par Julien Guyon, mathématicien, Le Monde, December 12, 2015 (in French). Available online here. - Euro 2016 : un autre tableau final est possible, Le Monde, June 24, 2016 (in French). Available online here. UEFA Champions League: How to Solve the Seeding Problem Starting in 2015, UEFA has put in place a new seeding rule for the Champions League, in order to protect more domestic champions. This is done by placing the domestic champions of the best leagues in Pot 1. I have suggested another, fairer way, which takes into account the relative strength of European domestic leagues. The new rule that I suggest for a fairer draw is described in the following articles: - Champions League: How to Solve the Seeding Problem, The New York Times, January 21, 2015. Available online here. - Ligue des champions : comment améliorer le tirage au sort, Le Monde, February 24, 2015. Available online here. - Ligue des champions : comment résoudre le problème des têtes de série, So Foot, February 24, 2015. Available online here. Flaws of the FIFA Rankings system Before July 2018, the FIFA Rankings calculation method was flawed in many ways. Loosing against team #1 or team #200 made no difference. Not playing friendlies could be very beneficial. The system penalized the hosts of major tournaments. Like many, I urged FIFA to use the Elo ranking method. FIFA listened and adopted the Elo calculation method in July 2018. However home advantage is still ignored, as well as goal difference. This is explained in the following articles: - A Better Way to Rank Soccer Teams in a Fairer World Cup, The New York Times, June 13, 2014. Available online here. - Pourquoi la France va dégringoler au classement FIFA, So Foot, June 23, 2015. Available online here. Rethinking the FIFA World Cup final draw The official rules used by FIFA until 2014 produced unbalanced groups, were unfair to some teams, and did not produce equally likely outcomes. I have suggested a new tractable draw procedure that produces eight balanced and geographically diverse groups, is fair to all teams, and gives equally likely outcomes. I have also suggested an adaptation of the method used by UEFA to draw the groups of the Champions League (Suggestion 1 in my SSRN article below). It is a good method but it is not perfect: all possible outcomes of the draw are not equally likely. This method has been studied by FIFA who adopted it for the World Cup 2018, in which the groups were much more balanced than in the past. The new rule that I suggest for a fairer draw is described in the following articles: - The World Cup Draw Is Unfair. Here's a Better Way, The New York Times, June 4, 2014. Available online here. - La FIFA doit aussi revoir le tirage au sort de sa Coupe du monde, Le Monde, June 4, 2014. Available online here. - Repenser le tirage au sort de la Coupe du monde, So Foot, June 4, 2014. Available online here. - El sistema del sorteo de grupos del Mundial es injusto. Cambiémoslo, El Pais, June 16, 2014. Available online here. - Interview in La Tête Au Carré on the French national public radio France Inter available online here (May 30, 2014; 600,000+ listeners). - This is an article in the French newspaper Le Monde promoting my work (May 14, 2014). - An academic article was published in Journal of Quantitative Analysis of Sports, 11(3):169-182, 2015. An extented version is available online on SSRN. - I was invited to present my research at various international conferences: MathSport International 2015, EURO 2015, the New England Symposium on Statistics in Sports (NESSIS) at Harvard University (2015), and at the Workshop on Fairness in Sports at Ghent University (2018).