4. Lucas Paqueta
Despite reported interest from Real Madrid and Barcelona, Paqueta chose to join Milan for a reported €35m fee from Brazilian side Flamengo.
The 22-year-old midfielder is regarded as one of the most exciting talents in South American football. Experts had compared him to Milan legend and fellow Brazilian Kaka.
But like a certain Krzysztof Piatek, Paqueta has struggled to hold down a spot in the Rossoneri line-up.
The former Flamengo star has made just eight starts and may leave in the summer should things fail to improve.