'You can't measure the value of psychology with numbers'

Is the link between psychological support and improved performance too difficult to draw with data?

Photo by Stephen Dawson on Unsplash

xG. xA. PPDA (that's passes per defensive action, for readers sane enough not to slavishly devote themselves to tactics columns in The Athletics). Data is now central to most debates about football. Transfer speculation inevitably leads to discussions about an individual's physical and technical stats. A manager's chan…