#7 Abdou Diallo
Market Value: €12 million
Transfer Fee: €28 million
Difference: €16 million
It is rare for Borussia Dortmund to splash out extravagant fees for players so there must be something about Abdou Diallo which led to the German club paying €28 million for his services this summer.
Having spent a season at Mainz 05, the 22-year-old impressed throughout his 27 appearances for the club and made the move to Dortmund to continue his development. The France Under-21 captain is certainly a towering presence in defence and has a lot of potential but paying €16 million more than market value for any player is a huge risk and adds pressure to his performances.
So far, the Frenchman has played three times for Dortmund and it will take some more time to see if he can make the step up from having some potential to fulfil the expectations placed on his shoulders.