4: Juan Mata | Chelsea to Manchester United
When Jose Mourinho allowed Juan Mata to depart Stamford Bridge in January it created one hell of a storm amongst fans and journalists alike. Not only was the Spaniard their two time Player of the Year, but he remains an exceptionally talented creative midfielder.
On his part the move to Manchester United isn't all too bizarre given the fact that he was being slowly edged out into the cold at Stamford Bridge, but with the Red Devils now looking a sure-fire bet not to be competing in the Champions League this season, as well as having still struggled massively in the league even after his arrival, he may be beginning to second-think his impulsive transfer.
Mata remains a world-class asset on his day, but playing under David Moyes at the moment has become something of a risk. Sure there's every chance United will return to their platform at the summit of English football after a healthy cash injection this summer, but if they don't then the 25-year-old might have run himself into a dead-end.