Number 5. Anderson
One of the more expensive transfers for Manchester United at the time, midfielder Anderson is not like most players in this list.
Despite miraculously staying at the club for eight years, Anderson never really amounted to anything. Over the course of those eight seasons, he only played 105 games, and scored an underwhelming five goals.
At the time of signing Anderson, he was 19 years old and looked to be a promising player for the future midfield, but quickly fell off. He was eventually transferred in the 2015 January transfer window to home town club Internacional.