By Jacob Leeks Cristiano Ronaldo refused to track back to help out the defence when playing for Manchester United, forcing Sir Alex Ferguson into a tactical switch. Ronaldo became a superstar during his first spell at United, winning three Premier League titles, the FA Cup and the Champions League. He was also named the top-flight’s Player of the Year twice and won his first Ballon d’Or while at Old Trafford. But while the Portuguese attacker was the star of United’s all-conquering side, Ferguson also had to work around him. Ronaldo would refuse to track back with his marker while playing for …