If new leadership comes in because they are trying to solve a problem created by an existing team, then it's easy to believe that the existing team is going to continue doing whatever they did originally that caused the problem. So it's not necessarily that the leadership knows the people they bring in and don't know the people that were there before, but they know that the people they bring in acted in a way that had good enough results they want to work with them again and that the people who are already there acted in a way that had bad enough results that they were hired to fix things.