#2 Shaun Wright-Phillips
Shaun Wright-Phillips, arguably England's most propitious player at that time, joined Chelsea in 2005 for £28.35m from Manchester City. After a successful spell with City, a lot was anticipated of the pacy winger but the England international failed to deliver terribly.
His move from Manchester City to London proved to be a risk and he was erratic in his first season, earning only 15 starts in an already strong Chelsea side. He also ended up missing out the England squad for the 2006 World Cup in Germany.
Wright-Phillips made a total of 81 appearances at the club scoring a pitiful 4 times and even though he was given a more consistent role under provisional manager Avram Grant, the winger failed to make his presence felt and was soon sold back to Manchester City thus ending an expensive mistake of Chelsea.