A few years ago, there was one of those radio debates between a football statistician and an ex-footballer.



These conversations usually feature a predictable ending: the statistician comes up with a figure which suggests something that goes against the consensus and the ex-footballer laughs him out of the studio, rubbishing the idea that the beautiful game can be solved by spreadsheets and algorithms.



On this occasion things were slightly different.



Opta’s Duncan Alexander produced an array of intriguing numbers, and former Liverpool midfielder Ray Houghton seemed genuinely interested.



Houghton’s only suggestion was a part of the game analysts hadn’t found a metric for. “The one thing you don’t yet have,” he said, “Is something that shows the importance of stopping running. The best players know when to stand still.”



And it was — at least at the time — a decent point. This was 2013,...