Scot launches staunch defense of Manchester United . Former Louis van Gaal boss is regarded as one of the best managers in world football . United have struggled since the Scot left in two decades . Manchester United charged with restoring club 's fortunes .
Rio Ferdinand launches staunch defense of Alex Ferguson . Former Manchester United boss is regarded as one of the best managers in world football . United have struggled since the Scot left in 2013 . Louis van Gaal charged with restoring club 's fortunes .