#3 Dani Ceballos (Real Madrid)

Last summer's transfer window was one to forget for the Real Madrid faithful. Fan favourites like James Rodriguez, Alvaro Morata and Pepe all made their exit, and the club struggled to buy suitable replacements for them. Perhaps their most high-profile signing was Dani Ceballos who has been far from impressive this season.
The attacking midfielder made a name for himself at Real Betis while operating as their chief playmaker and caught the attention of Real Madrid. They bought him in July 2017 for a reported €18 million.
However, he has endured a gruelling debut season and has failed to deliver. He has started only 2 league games all season and has scored just twice.
Zidane has had his own difficulties this season, tweaking his system often to accommodate Isco and Gareth Bale. Ceballos has been largely frustrated with a lack of playing time and there are even reports of him seeking a move away from the club.
Madrid are set to spend big this summer which may prove to be fatal for Ceballos' Madrid career.