IMO, it doesn't tarnish his "legacy". He gave us 5 good years, brought some of the Hilton Magic back, gave us some great wins, and also was a class act as a head coach the entire time (unlike Fran for instance).
However, it does change my view of him as a person somewhat.
I thought he was "one of us", and he isn't.... he's just like any other head coach (Calipari, Saban, etc) who is mostly in it for themselves. We all knew he would leave someday for the NBA, I just didn't think it would be before he accomplished really any of his goals he set forth when he came here.
And never in my wildest nightmares did I ever think he would leave before Niang, Naz, Morris, etc finished their careers here. These were "his guys". These are the guys that did all the work to get Fred's name even mentioned as a candidate for a head coaching job in the NBA. These are the guys that put everything on the line for Fred day in and day out to get to where they all wanted to get.
Heck, Niang even came back for his senior year because there was unfinished business. I NEVER thought Fred would even consider leaving before this "unfinished business" was completed. Which brings me to my next point... Fred is not this super "competitive" guy we've all been told he is either. A super competitive guy would not go out with a horrible loss in the first round to UAB in which you were clearly outcoached badly. A super competitive guy would not leave before accomplishing really any of his goals. And he would definitely not leave guys like Niang, Naz, McKay, Morris, Thomas, etc hanging like this and quitting on them.
So Fred's legacy IMO is not really damaged because he's always done good things for ISU as a ball boy, player, and now head coach, however, my view of him as a person has definitely changed for the worse. It bothers me a LOT to say it, but he's just like every other greedy head coach out there that only thinks about himself and his needs. And that is sad.
We all thought Fred was different in that sense, but it turns out that he isn't. I think his ego has gotten the best of him. I fear for the decision he's making too. IMO, it's not going to turn out well for him. I'm not sure if he's aware of what he's getting into. People in Chicago could care less about Fred Hoiberg. You will not be worshipped there like you were in Ames. You're just another head coach trying to live up to Phil Jackson and Michael Jordan in Chicago. Good luck with that. They will chew you up and spit you out at the first chance.
I hope Fred is considering retirement soon because that's probably where he's headed in the next few years. NBA coaches last fewer than 4 years on average. And I hope ISU doesn't bring him back someday either anymore.