Your son just got a golden ticket to USNA. Is this his Plan A? If so, accept it quickly. He will be inducted into the Naval Reserve when he reports, and take classes to prep him for Plebe year such that if he studies hard, he will find that academics are going to be one less stressor in an incredibly stress-filled year. He will have a year of maturity and will be introduced to military life and the military "way" of doing things and will be looked upon by the Cadre during Plebe Summer as being more squared away than the garden variety high school graduate. Usually (but not always) he will be assigned minor leadership roles during the summer ("Jones, form these people up and take them to sick bay, NOW!!"). We had a number of NAPsters in my company and every one of them spoke highly of that year and considered it good fortune to have gone there first.
As a unappreciated bennie, when he puts in his 20th year of active duty, for pay's sake that extra year at NAPS kicks in and he is paid for 21 years of active duty. Doesn't work unless he puts in the full 20 though.
The only way he can screw this deal up is to (1) get poor grades (2) rack up conduct or honor offenses and NOT get a recommendation from the Commanding Officer. Pretty rare but it does happen.