Compmom and cameron121 made important contributions to this discussion. Admission decisions are not based on rank ordering students from the most to the least qualified applicants and drawing a line under the least qualified of the most qualified and sending admissions letters to those above the line. Instead, elite colleges have many extremely qualified applicants among whom to choose.
So, whom does the school admit? Well, I am sure the very qualified legacies who are still young enough to attend college are admitted. After that, admissions decisions are designed to build a class. So, if the school needs a good student who excels at basketball and plays the same position as the star player who just graduated, then I would expect admission. If a program has more tenured professors than majors, then well qualified applicants seeking that major are likely admitted. If a well-qualified student is the first person from a rural area of North Dakota applies and has something to add to the class, then that student is apt to be admitted. In contrast, the many qualified applicants who want to major in an area with scads of existing majors are less likely to be admitted. Each year a class that meets university needs is admitted. Those not admitted are not judged to be unqualified or deficient, but just not what the university needs and is looking for this time.
Admissions folks, then, are looking for those well-qualified applicants whom the university needs to fulfill its needs and admits excellent candidates who have something special as Cameron 121 pointed out. It’s all about selecting a class from a embarrassment of riches in terms of excellent applicants. It’s not personal when qualified applicants are not admitted, but is wildly disappointing when you are denied. Please watch Legally Blond 1 to see how a member of the new class at Harvard Law was selected.