For me the one that strikes me is Kevin (Keegan) Hofland. As a youngster with PSV he was thought of to be an amazing defender, and all the top European sides were flocking for his signature, it was around the same time we played Netherlands in 2001. His career never really went anywhere, went to generally mid-table team Wolfsburg for a few years, but now is back in Holland playing for Feyenoord.