For the record, McClown didn't win the Uefa cup, they got spanked.
Also FC Twente, dutch league is weird, in his first year in charge they came 11 points behind AZ Alkmaar, who had finished 11th the year before. Twente had finished 4th for the previous 2 seasons, the next season Alkmaar lost a shedload of games under Koeman who had just come in, and they fired him.
He certainly didn't do badly at Twente, but he didn't take an 11th placed team and turn them into champions, he took an established top 4 side, watched Ajax in their crap years, and watched AZ drop out of the top four all by themselves.