A phone-free Yellow Wall: are Dortmund urging fans to be present or policing them?

It makes sense that sports teams want to keep influencers out of their games. The battle some clubs are waging with their fans, however, is a different dilemmaBy all appearances, things on the Yellow Wall seemed as they always had been. The stadium announcer hollered out the first names of Borussia Dortmund’s starting lineup and the supporters responded with their…