A great many bad managers think of their work as the equivalent of a rocket launch. Punch in a few coordinates here and there, then push a button and, if their staff hasn't let them down, all should go well. [Note to NASA personnel: I know it is much more complicated.]
Good managers are inclined to regard their work as the captain of a ship. Storms and currents will move the ship off-course and it is the captain's job to adjust so, in the end, the destination is reached. A captain who announced at the beginning of a voyage that the proper course has been charted and so that question has been resolved would not be a captain for long nor would the person be thought of as rational.
Captains are expected to anticipate and handle storms and currents. A "fair weather" captain would be of little use. So too with managers. Workplace storms and currents are not enjoyable but they are part of the process and managers who accept that will have the foresight and flexibility to deal with them.