If the MOC does not submit a full slate, regardless of method used, regardless of how many slots the MOC might have available, that means a good handful of people will not get a nom, and be eligible for an offer of appointment from the national pool, assuming they are fully qualified.
Those who are appointed from the pool per the SA guidelines, do not have those appointments charged to the elected official, even though that was the original source of the nom required to be placed in the pool.
The SAs keep careful track of how many appointments are actually charged to the elected official and work with the official’s staff. It may appear to be absolutely true that X number of candidates nominated by Rep Y were offered an appointment, but behind the green curtain, some of them may actually have their appointments charged elsewhere.
I don’t understand why a full slate would not be chosen so as to offer qualified others a chance at an appointment charged to another source.