#2 Matteo Darmian - Market value 12 million euros

Darmian had a barnstorming start to his United career when Van Gaal signed him in 2015, turning in a series of accomplished performances to indicate that United had finally found a long-term solution to the right-back problem, which they have faced since Gary Neville retired.
As it happens with many new players in the Premier League, though, English winter came and instead of celebrating Christmas and New Year with his family, Darmian was undergoing the grueling English tradition of non-stop games (and injuries/suspensions) during December. He never seemed to recover from the culture shock.
In the meantime under Mourinho, Antonio Valencia and Ashley Young completed their metamorphosis as full-backs that started when Van Gaal was manager. Darmian has been a stop-gap every since. A return to Italy, most likely with Juventus, beckons.