While bureaucracies are formally under politicians' control, politicians are elected, and bureaucrats are not. They easily outlast politicians, and definitely set their own conditions for politicians to follow if they don't want their orders obstructed and sabotaged.

I would hazard to say that it's in the bureaucrats' best interest to have politicians unpleasant and unqualified, of the "both worse" kind. Interestingly, quite often election candidates tend to resemble this description, at least if their opposition is to be believed.