Have said this all along.
Because of the numbers and because of the prep schools they can sign a whole bunch of guys who are late developers, guys who are excellent players but a couple inches short or 30lbs light. The ones that develop end up playing, those that don't get their free educations.
It has also been stated by those close to the programs that their records on the field are a direct reflection of how tight or loose the school administrations are about admitting athletes who are marginal academically.
I assume you know, but those educations aren't free. Same goes for NROTC and the like, they have a payback that lasts years.
As far as admissions go, in my limited understanding (but having know several midshipmen who this applied to), they reach out to underserved communities. It's not just for athletes, but applicants in general. So yes, that helps with athletic numbers, but they still have to meet the standards once they arrive. In large part, the prep is a year of teaching those with promise what their high schools didn't offer, or other gaps. Some high schools, believe it or not, don't offer proper physics, advanced math, and so on - especially at inner city and rural places. My experience is anecdotal, but three of the five kids we sponsored were considered minorities. Two of those three thought they were admitted via waver based on disadvantages they grew up with: one was from a poor family in Orange County, CA who attended Servite's sister school on a similar scholarship, and the other was a rural SE Colorado kid from whose parents never attended college. The third was a rockstar who could have gone just about anywhere she wanted.
Having watched several Navy practices and knowing people associated directly with the team, I promise there weren't 94 x 4 or 5 footballers at practice. The academies recruit athletes because their future professions generally demand that type of person. I had a state champion wrestler friend who went to Air Force and tried to make the football team. He spent a couple years on the scout team, then took up another sport and focused on academics - he became a surgeon. They are all required to participate in some type of sport. Our five participated in: varsity cross country, crew coxswain, flag football/drill, karate, and varsity wrestling.
Don't get me wrong, if it's proven they are somehow cheating the system, it should be corrected. You have to figure most of those kids counted the academies as their best option, few go based solely on patriotism, so they aren't really expecting to make it to the pros. The one thing that changes the dynamic a bit is the recent loosening of rules when it comes to going straight to the NFL, NBA, MLB, or whatever. I'm not certain how the payback component works, whether it's deferred or waived, though I seem to recall it's deferred.