If they've known about it for years that the guy is a control freak who cannot delegate (which i suspect they have) perhaps it would have been prudent not to have given the guy a three year contract and making it abundantly clear they were happy with everything he was doing.
Dein, Edelman and Friar all left within a year of each other....Fiszman remained in name but was battling against ilness, Wenger grabbed power in the vaccum left by these individuals.