The FBI had people like Strzok and Page who thought they were superior (newsweek.com) to the general population and would decide the election for them (nypost.com).

They were compromised when Comney took over and started removing people who wouldn't follow orders regardless of obvious lack of constitutionality.

Many many many good lawful and morally good agents retired as a result. If they had more than 10 years, they took an early retirement