Totaalvoetbal is the label given to a tactical concept in which any outfield player can take over the role of any other player in a team. Jack Reynolds, coach of Ajax before the Second World War, was the pioneer whose ideas of a universal footballer, who can take on any task, were adopted by the likes of Valeriy Lobanovskiy and Ernst Happel to design modern 4-3-3 and 1-3-3-3 systems. Rinus Michels, who played under Reynolds, became manager of Ajax himself in 1965 and refined the concept into what is known today as Totaalvoetbal or Hollandse school, using it in his training for the Ajax squad and the Netherlands national team in the 1970s. It was further refined by new Ajax manager Stefan Kovacs, after Michels left the club for Barcelona in 1971. Dutch forward Johan Cruyff was the system’s most famous exponent. Although Cruyff was fielded as centre-forward, he wandered all over the pitch, popping up wherever he could do most damage to the opposing team. This resulted in a need for a dynamic system. Cruyff stayed true to those principles when he worked as a coach. Until today, this kind of tactical theory is regarded as revolutionary, as many highly skilled sides like Barcelona have tried to follow the ideal of Totaalvoetbal, with the Ajax team of the early 1970s being the prototype.