There was 1 superstar on the market this year and the Bulls went hard for him. They went hard after Lebron/Wade/Bosh the year before that too.
Sometimes you have good plans, but they don't come to fruition. It sucks but that's life. I don't think the Bulls FO is incompetent or deserving of losing their jobs just yet, because they've attempted to make these big FA splash type moves that you want them to make, they just haven't been successful at it for various reasons (many of which are external reasons, not of their own doing)