In the free-weight room the other day, I noticed that I had the smallest pectoral muscles of anyone in there. Yet I can do 60 pushups! Something doesn't add up here.
Of course, men (mostly men) who are in that room in the first place are a self-selecting group. Walking down the street I am slightly more muscular than average, but in the weight room I am scrawny.
Of course, I am also only 5' 8" and 160 lbs. Probably everyone else lifting weights were between five-eleven and six-four, and 190-230, I would guess. I am strong relative to my weight. I am also 30 years older than most of them, so I feel good just being there, even if I am the proverbial 98-lb weakling.
So I guess the metaphor here is about comparing yourself to other people. You could feel one way walking down the street, among non-academic civilians. You are smarter than them. Another way in your own department, a self-selected group of people all working in the same discipline, and another way in the profession, where the smartest guy or gal in one particular department might be mediocre on the national scene.