When he arrived, Bielsa had watched their 38 league games last season, writing all the details on colour-coded spreadsheets. And that really is all the details – he says: "There are 36 different forms of communicating through a pass." He watches thousands of games, building a footballing taxonomy, like some kind of botanist. If a player does something new, he labels and stores it, learning from it. Teaching from it, too. Few are so didactic: he once drew on his shoes to show players exactly which part of their foot to use, wearing them for days after. Video sessions can last five hours and players joke that they do not dare make a mistake lest the green laser rest upon them and Bielsa demand a convincing explanation.