1. Michael Ballack
The German was a powerhouse and instead of staying in the Bundesliga he moved from Bayern Munich to Chelsea on a free transfer in 2006. He probably couldn’t go back to Leverkusen and decided to join the next big thing, Chelsea.
Ballack took a bit of time to get used to the English game but once he got into the groove there probably wasn’t a better central midfielder in England at the time. Ballack played 166 games and scored 25 goals for the Blues and won a Premier League and three FA Cups, not a bad return for a free transfer.