5. Kaka | AC Milan
Highest market value: £61.5m (d.o.v - September 11 2007)
Current market value: £7m
Position: Attacking midfield
Remember when Manchester City tried to sign Kaka for €100m - that was just one year after his value peaked. City dodged a bullet there.
He was at his most valuable to AC Milan in 2007, a few months after their Champions League win over Liverpool.