| Abstract: |
In this paper we consider trends in the distribution of player talent across
association football clubs over time. Player talent is the most important
prerequisite for team success in professional sports leagues and changes in
players' assortativeness in regard to the clubs they play for may arguably be
an important factor for changes in competitive balance. We offer a new
approach for measuring player talent and its distribution - the partial
correlation of each player with the goal margin. We use this measure to
analyze the degree of competitive balance over time. This approach enables us
to examine how player mobility drives competitive balance over time. Empirical
results are based on 19 seasons of the first two divisions of the German
Bundesliga as well as domestic cup games. Our results show a decrease in
competitive balance over time; better teams tend to attract increasingly
better players. We show that this is driven by an increasingly unequal
inter-divisional distribution of teams, coaches and players, as well as
increasing assortativeness in the 1st Bundesliga. We further demonstrate that
player transfers between Bundesliga teams results in assortative matching
between players and teams. These domestic transfers do not, however, explain
the reduction in competitive balance over time. Furthermore, we show that UEFA
Champions League payments may have contributed to the reduction in competitive
balance over the last two decades. |