I think this is the a big piece of the issue for sure. You normally see a successful GM bring as much of his team as will follow him. Did Yzerman bring anyone? That probably should have been a red flag from the get go.
That and the near total lack of accountability for the poor FO performance with trades and FA is another red flag. You can envision Yzerman being the total Mensch and saying - well it's my fault they didn't do better, but if you are going to be that guy and take the blows for everyone, a sports FO is probably not the long term job for you.
Even Al Avila replaced people.