8 players Chelsea were WRONG to sell: Letting Arsenal sign Petr Cech one of many Blues MISTAKES

5) Arjen Robben

A world class winger who Chelsea for some reason let go early on, Arjen Robben has gone on to enjoy great success with Bayern Munich.

6) Kevin De Bruyne

Allowed for some reason to join Wolfsburg, Kevin De Bruyne now looks one of the best attacking midfielders in Europe, and had better stats than Eden Hazard last season.