As one professor in my MA program I told me, an A in grad school indicates you're doing the right kind of work, an A- that you're close but not quite where you want to be. A B+/B is sort of a warning sign that you need to do better if you want a shot at good programs. It is plausible that someone could sleep through breadth courses and do extraordinary work in AOS/AOC areas, but you would want those lackluster courses/profs you took them from as far away from you as possible. It would seem difficult to have many of those lackluster courses and not have it creep in to the forefront of one's portfolio.