6. Letting Paul Pogba Go
/AP/Press Association ImagesIn 2012, Sir Alex Ferguson
admitted his 'disappointment' over midfielder Paul Pogba's decision to leave Manchester United, a departure that may yet go down as one of the most costliest mistakes in United's history. Pogba spent an uneventful three years at Old Trafford and, after emerging from the club's youth academy in 2011, made only three appearances for the senior side. Perturbed by his lack of playing time, the Frenchman agreed to join Juventus in 2012, where he has gone on to establish himself as one of Europe's most sought-after midfielders. Former United defender Rio Ferdinand said earlier this month that he thinks Pogba could one day go on to
establish himself as the best midfielder in the world, and were he to be sold today, the 21-year-old would command a
reported market value of £50 million.