4: Bebe
Portuguese forward who was signed from Vitoria de Guimaraes in the summer of 2010 for an undisclosed fee believed to be in the region of 9 million euros, with the player’s arrival at the Theatre of Dreams being greeted with more than a few raised eyebrows at the time.
And after just two top-flight appearances in his debut campaign at the club, it became abundantly clear that the player was way below the standards required of a United player, and while Bebe is still technically at the club, he has not played for them since, spending loan spells at the likes of Besiktas, Rio Ave and now Pacos de Ferreira.
3: Kleberson
Manchester United had to fight off interest in the highly rated Brazil international from a whole host of big-name European clubs in order to land the Atletico Paranaense midfield player in the summer of 2003 for a fee of £6.5m after the player had shone for his country in the previous year’s World Cup finals.
However, after getting injured in just his second match for the Red Devils, it was downhill pretty much thereafter for Kleberson and two years later after only 20 league appearances and two goals for the club, the Brazilian was on his way to Besitkas for 2.95m euros.