David Sumpter in his book Soccermatics simulates an process of tactical evolution in soccer. Teams in a 20 club league are initially equally divided by the use of four different styles of play. The last six teams in each season are replaced by teams with the same style of play of those that finished in the top six spots the season before. Over time, some styles disappear, but for more than 40 simulated seasons at least two styles survive: it is an example of polymorphism. In evolutionary processes, agents do not consciously decide, but they are one type or another, and the most successful types expand in the population. European soccer has lived its own evolutionary process. FC Barcelona started to import Dutch managers in the 1970s because they were successful in Europe. Rinus Michels, Johan Cruyff, Louis Van Gaal and Frank Rijkard tinkered with a similar model, total football (which had roots in several European traditions), following a trial and error process. Rijkard, not a particularly gifted manager, introduced perhaps by chance (a mutation?) a key innovation: replacing the offensive, short and technical central midfielder of Cruyff and Van Gaal by a more defensive player (Davids, Cocu), and sending Xavi Hernández closer to the penalty box. Then Guardiola found the perfect player for the position of defensive midfielder, Sergio Busquets, and had Xavi and Iniesta in the other two positions in the midfield at their best ages, accompanied by a young and energetic Messi. Now Xavi is no longer there, and Iniesta is ageing. The team is too dependent on three fantastic forwards, and somehow the rich total football game based on short passes and small spaces is being left behind. But not for long, if Xavi Hernández completes his training as a manager (please, no need to sack Luis Enrique before) and we soon recover the evolutionary thread that started in the Netherlands in the 1960s, arrived in Barcelona a few years later, and marvelled the world in the first decades of the European Champions League.