Dad,
As stated above, the answer to your question depends on the service in question... There are only a very small number of slots (if any, on an annual recurring basis) for USCG, USAF and USA. Since USMMA is already tied to the Department of the Navy in many respects there is a long standing relationship with the USN and USMC, but even then the number of dedicated slots is pretty small.
The USN program is completely different from the other services because your son or daughter is already in the Naval Reserve as a MIDN at USMMA... Selection to flight school follows a special program within navy accessions that places the KP MIDS in a different category - not competing against USNA, NROTC or OCS.
That said… Kings Pointers have many more options available to wind up in naval aviation and certainly stand a better chance than other institutions, including USNA.
Selection is competitive for USN slots with a limited number of pilot and NFO billets offered each year. But unlike USNA, not being selected on the first round is not necessarily the end of the road. There were several graduates in my senior year that did not get one of the pilot or NFO slots offered to KP that year in the first round, but did get picked up before graduation after the other Maritime schools didn't fill their billets. Everyone that applied was selected. The year before I graduated there were several graduates that applied but were not selected at all. They took their USNR-MMR (reserve) Commissions after graduation and applied to the Navy's lateral transfer board (requesting a lateral transfers from Merchant Marine Deck/Engine Officers to Student Naval Aviators) and were picked up. I also knew two football players who both sailed for three years in the merchant marine before activating their commissions and going to flight school. Both, by virtue of their seniority were their class leaders since they were LTJG's when they reported for training.
So, yes... selection is competitive. But, provided your son or daughter is fully qualified, and FULLY MOTIVATED there are other opportunities NOT offered to USNA and NROTC graduates (those young men and women must select an alternate field if they don't get their first pick and will fill their service obligation on active duty).
Good luck,
USMMECOM
KPStore