The problem with mediocrities is that they don't know they're mediocre. Mediocrities think they're extraordinary, which makes them particularly irritating to others, but also highly entertaining, depending on your perspective. Psychologists call this the “Dunning–Kruger effect,” named after two Cornell University researchers who found that incompetent people are unable to recognize their lack of skills, vastly overestimate their abilities, and are also unable to identify talented people.
A manager’s inferiority complex leads to arrogance and self-importance, so this job will never find the right person.