Sky Sports pundit Paul Merson has identified one of Manchester United’s biggest issues since Sir Alex Ferguson called it time on his legendary career at Old Trafford. Ferguson’s 26-year dominance at United saw the Red Devils climb the echelon of world football and compete for Premier League titles on a regular basis. The 82-year-old Scotsman was instrumental from the United dugout and behind the scenes at Old Trafford, with Ferguson playing a key role in transfers. Ferguson retired from football in 2013 after leading United to their last Premier League title, with the Red Devils struggling in …