1. Introduction

The demographic analysis of squads is a key research area of the CIES Football Observatory. The 32nd edition of the Monthly Report analyses the age structure of teams in 31 top division European leagues. This allows us to show discrepancies on an international level, while also investigating the links between the age structure of teams and success.

Leagues and clubs greatly differentiate themselves with regard to the age of their squad members. While the most competitive teams and championships are not the youngest ones, they are also generally not those with the most seasoned players. The gaps observed also reflect the existence of distinct cultures and strategies.

The study stretches over a period of nine years between 2009 and 2017. In order to be included in the analysis, a footballer had to be present on the 1st of October in the first team squad of the clubs surveyed. Moreover, he should have already played in domestic league games during the season of reference, or, if this was not the case, to have taken part in adult championship matches during each of the two previous seasons. The second and third goalkeepers were considered in all cases.

​Figure 1: leagues and players surveyed (2009-2017)​

2. Age gaps

The age of teams across Europe vary widely according to league. The Cypriot top division is the competition having regrouped the most seasoned players between 2009 and 2017: 27.5 years on average. Italian Serie A teams also have ageing squads (27.1 years). This is about three years more than in Croatia and Slovenia. The average age of players for all of the 31 top divisions and nine years analysed is 25.9 years.

​Figure 2: average age of squad members, by league (2009-2017)​

Considerable differences in the average age of squad members also exist between teams. Figure 3 lists the clubs with the oldest squads since 2009 in the 31 top division leagues surveyed. The record high was measured for Chievo in 2015: 30.6 years. Two other teams had a squad of players on average over 30 years old: the Cypriot sides AEK Larnaca (2016) and APOEL FC (2012). Eight clubs out of the ten oldest teams are located in the Mediterranean area (Italy, Cyprus, Turkey and Greece). This is a first indication of regional peculiarities.

​Figure 3: oldest squads, 31 top division European leagues (2009-2017)​

At the opposite end of the spectrum, no team since 2009 has had a squad as young as FK Rad Belgrade in 2013: 21.0 years on average. None of the ten youngest teams are located in the most competitive European leagues. Six of them are located in Serbia, Croatia and Finland. The very young squads of some of the clubs in the top ten rankings primarily reflect financial troubles. This was notably the case for Alki Larnaca and Heart of Midlothian in 2013.

​Figure 4: youngest squads, 31 top division European leagues (2009-2017)​

The average age of players also vary greatly according to position. The general rule is that goalkeepers are older than defenders, defenders are older than midfielders and midfielders are older than forwards. In the 31 leagues surveyed, goalkeepers were almost 1.5 years older than forwards. This is mainly due to the different physical attributes required by this position, as well as the greater importance of experience for goalkeepers. This is also true for defenders with respect to midfielders and forwards.

​Figure 5: average age per position, 31 top division European leagues (2009-2017)​

Another general rule is that the most competitive leagues generally bring together more seasoned players than the least competitive championships. The statistically significant negative correlation between age and UEFA ranking confirms this observation. However, there are many residuals. Dutch and Croatian clubs, for example, clearly over-perform in European Cups with respect to the average age of their squad members. Conversely, Cypriot teams do not achieve the results that one would expect with regard to the experience level of their players.

​Figure 6: correlation between average age and average UEFA ranking per league (2009-2017)​

A correlation also exists between the sporting level of clubs and the average age of their squads. The sporting level is calculated using the CIES Football Observatory club coefficient. This exclusive classification method takes into account the performance of national association representatives in European club competitions, the division of the employer club in the domestic league and results achieved.

Generally, clubs that are more competitive have older squads. This rule applies perfectly to each of the four lowest club level categories presented in figure 7. However, no significant difference was observed for clubs in the three top categories. This finding reveals that after a certain threshold of sporting and economic power, the age structure of clubs tends to converge. Our analysis suggests that the optimal average age of squad members is between 26 and 27 years.

​Figure 7: average age and sporting level as per CIES Football Observatory club coefficient (2009-2017)​

3. Age for champions

None of the ten youngest champions during the period analysed belong to the most competitive European leagues. The Slovakian side AS Trenčín tops the table ahead of two Dutch clubs: Ajax and PSV Eindhoven. The latter examples show that it is possible to win with very young squads even in countries ranked in the top ten of the UEFA table. However, this is generally not the case at the very top of the European football pyramid. The youngest big-5 league champion during the period surveyed was Borussia Dortmund in 2011/12 (24.7 years).

​Figure 8: youngest champions, 31 top division European leagues (2009-2017)​

The top ten list of the oldest clubs crowned champions from 2009 to 2017 shows the specificity of the Italian case. Three Serie A teams are among the four champions with the most seasoned squads. Another team from a country with a favourable disposition towards experienced players tops the table: APOEL Nicosia from Cyprus. They are also the only champions whose squad members were on average over 30 years old on the 1st October of the season when they won the league.

​Figure 9: oldest champions, 31 top division European leagues (2009-2017)​

The comparative analysis of the average age of champions between leagues also reveals cultural differences in the perception of the most favourable age structure for a squad. At one extreme, the youngest champions are to be found in the Netherlands (24.2 years), where teams pay great attention to the training and development of young talents. At the other extreme, Cypriot champion teams had the oldest squads over the period surveyed (28.8 years).

​Figure 10: average age of champions, by league (2009-2017)​

4. Conclusion

Squad assembly is an art that must be carefully mastered to be successful. Evidence shows that a good balance is necessary to perform durably at the highest level. A balanced age structure permits young footballers to develop alongside more experienced players and progressively replace them as pillars of the team. This is also a necessary prerequisite to maintain a satisfactory level of stability and performance over the long term.

While no single truth exists with regard to the relationship between age structure and success, the median age of champions in the five major European leagues between 2009 and 2017 is a good indicator of a possible benchmark. This figure is 26.5 years old. In accordance with previous findings, we can state that in order to achieve sustainable success, it is important for clubs to have as many players who did not celebrate their 27th birthday than footballers over this age threshold.