By László Csató
Penalty shootouts are nerve-racking for even the most skilled of footballers. And there’s good reason to fear them since science suggests that shootouts are more about luck than technical ability. The team that kicks first has a significant advantage because of the psychological pressure it puts on their opponents. After two tense penalty shootouts on Sunday that put Russia and Croatia through to the World Cup quarter-finals at the expense of Spain and Denmark, Euronews speaks to an economist about what would make one of the most dramatic and controversial moments of the competition fairer.
Why are penalty shootouts controversial?
Before 1978, when a FIFA World Cup game in the knockout phase was tied at the end of extra time, the winner was decided with a coin toss. Penalty shootouts were introduced to make the outcome less of a lottery. But they are still often seen as having more to do with chance than which team is the stronger competitor.
Under the current rules, the referee tosses a coin and the winner can decide whether to take the first or the second kick. After that, teams A and B take five penalties each in an alternating pattern, that is, according to the sequence AB|AB|AB|AB|AB. If the scores are level after five rounds, the sudden death stage starts in the same order AB with additional rounds of one kick each until the tie is broken.
This rule can be called ABAB.
Since most penalties are successful, the player taking the second kick is usually under greater mental pressure, especially from the third or fourth penalties onward, when a miss could mean the immediate loss of the match. Statistical evidence shows that the team kicking first wins in around 60% of the cases. Since this fact is widely recognized, the team winning the coin toss almost always chooses to take the first kick.
What other options are football authorities considering?
In order to reduce this bias, football’s rule-making body IFAB (International Football Association Board) decided to test an alternative system called ABBA, when the five penalties are kicked according to the sequence AB|BA|AB|BA|AB. The same pattern, which mirrors the serving sequence in a tennis tiebreak, would continue if the shootout goes to sudden death. The trial was initially scheduled at the 2017 UEFA European Under-17 Championship and the 2017 UEFA Women's Under-17 Championship in May 2017 and was extended to the 2017 UEFA European Under-19 Championship and the 2017 UEFA Women's Under-19 Championship in June 2017. The first implementation of the new system was a penalty shootout in the Women's Under-17 Championship semi-final between Germany and Norway on 11 May 2017. It was also applied in the 2017 FA Community Shield, where Arsenal, the winner of the 2017 FA Cup Final, had won an ABBA penalty shootout against Chelsea, champions of the 2016–17 Premier League.
The current football rulebook (Laws of the Game 2018/19) explicitly says in its section discussing future plans that IFAB will focus on fairness and integrity issues, and, working with its expert panels, will consult widely on a number of important Law-related topics, including a potentially fairer system of taking kicks from the penalty mark.
Scientific researchers have suggested some further designs for penalty shootouts, all of them starting with the usual coin toss. The Catch-Up Rule takes into account the results of the preceding round by giving an opportunity for the team performing worse to catch up. Basically, it alternates the team kicking first as ABBA, however, if the team kicking first fails its penalty and the other succeeds, then the order remains unchanged in the next round, to provide an advantage for the underdog. Its variant the Alternating Catch-Up Rule applies the same principle for the first five rounds, but the team that kicks the second penalty in the first round will kick the first in the sudden death (provided that it is necessary).
Can you give an example?
As an illustration, consider the case when team A scores three penalties by missing the second and the fifth, while team B also scores three penalties by missing the second and the fourth. Since the first two penalties are successful (1-1), B kicks first in the second round, where both of them are unsuccessful (1-1). So A starts the third round, when both teams succeed (2-2), thus B kicks the first penalty in the fourth round, but it fails and A wins (2-3).
Since the (Alternating) Catch-Up Rule aims to equalize the winning odds, B remains the first kicker, and it succeeds, while A fails in the fifth round (3-3). The shootout goes to sudden death, where A kicks first according to the Catch-Up Rule, but B kicks first if the Alternating Catch-Up Rule is applied. Consequently, the Catch-Up sequence is AB|BA|AB|BA|BA (sudden death starts) AB|BA|AB…., and the Alternating Catch-Up sequence is AB|BA|AB|BA|BA (sudden death starts) BA|AB|BA…
What is the fairest approach?
On the basis of empirical research, it is a reasonable assumption that, with equally skilled players, the probability of a successful kick depends only on whether the player kicks first or second on around. Then the teams should have the same chance to win in order to level the playing field. Mathematical calculations reveal that the ABAB rule is very unfair. The ABBA and Catch-Up Rules are close to each other, but the Alternating Catch-Up Rule outperforms both of them, that is, it seems to be a promising candidate to guarantee fairness. This rule depends on the result of the penalties kicked in the previous round (at least between the second and the fifth rounds), but this complication can make penalty shootouts even more exciting. Application of the (Alternating) Catch-Up Rule also increases the probability of reaching the sudden death stage. Since any reform has significant costs, we think it is worth to choose a mechanism that is as fair as possible.
László Csató is a postdoctoral research fellow at the Institute for Computer Science and Control, Hungarian Academy of Sciences, and a senior lecturer at Corvinus University of Budapest