#1 Bebe (Manchester United)
Sir Alex Ferguson might be considered to be the greatest man to have managed a club in the Premier League era but that does not mean that the Scot did not make mistakes in his glorious career as the manager of Manchester United. While some cite his inability to retain key players such as Jaap Stam or Ruud Van Nistelrooy as the lowest point in his career, a large section of Manchester United fans will agree that signing Portuguese footballer Bebe without having ever watched him play was a hilarious yet costly mistake.
Bebe had joined Portuguese outfit Vitoria de Guimaraes in the summer of 2010 before Carlos Queiroz, the then assistant manager at Manchester United decided the time was right to bring Bebe to England and convinced Sir Alex to part with £7.4 million in order to activate his release clause in order to beat the likes of Real Madrid and Benfica to his signature.
However, once Bebe arrived in England, it became clear in a matter of days that he was not yet prepared for life in the Premier League as the hierarchy at the Old Trafford deemed that he did not have the adequate skill set to be involved extensively with the side. Bebe featured just 7 times for the Red Devils and scored twice and was ultimately sold to Benfica at the beginning of the 2014-15 season after a series of loans at Besiktas, Rio Ave and Pacos de Ferreira (where he managed to score 14 goals in 39 appearances).