I'm sure everyone remembered how a promising Nigerian CAM named Mikel was converted to a CDM in a very puzzling
move by Mourinho, and has played there ever since. But listen to the story of Makalele , the greatest ever CDM.

however at Celta Vigo (before he went to Real) Makalele was used as an attacking midfielder, or sometimes as a left winger. I remember him having reasonable dribbling ability and good vision for picking through balls and crosses. I fully expected him to play left wing for Real when he signed, but with Zidane nominally occupying that role in the galactico era, he became the deep lying midfielder, where his reading of the game that had previously been used to slide passes in between defenders was now utilised to cut out opposition moves.

http://defensiveminded.wordpress.com/2011/03/05/makelele-no-longer-playing-the-%E2%80%9Cmakelele-role%E2%80%9D/

from the comments.