For a while now, the belated success of Mikel Arteta at Arsenal has been a useful shield for under-fire managers to hide behind. Give me enough time and resources, they would say, and I can turn your fortunes around just like Arteta did at Arsenal. Now, there are certainly similarities between the situation Arteta inherited at the Emirates and the one Erik ten Hag sunk his teeth into at Manchester United. Two sleeping giants beset by flawed recruitment, a host of overpaid, underperforming players, and owners who would not know a good footballing decision if it slapped them squarely in the face…