There are several categories of appointment and sources of nomination. Two categories of appointment in particular, Qualified Alternate and Additional Appointee, require a nomination from any source (MOC, Presidential, Superintendent, etc). Most recruited athletes are appointed as Additional Appointees.
A well informed MOC using a Ranked Slate will rank a recruited athlete or any other candidate with an LOA at the bottom of the slate, thereby increasing the likelihood of multiple appointments from the district. The nomination guarantees the qualified LOA holder an appointment, while leaving the MOC's opening available to another qualified candidate from the district.
Most MOC's submit an unranked slate, in which case USMA ranks them according to WCS score. The highest score wins the district, if qualified, irrespective of recruited athlete or LOA status. LOA holders without the highest score receive an appointment from another category, although how admissions eventually charges the appointment may be very different from how the appointment was determined.