'2019 Comments are spot on.. NASS is a promotional, awareness program. Of course grades and scores have to be good enough to be eligible or qualified for Admission (with the recognition that many improve SAT/ACT scores between Junior and Senior year), but the top scores are not necessarily going to beat out lesser scores. As I've said here before --that kid from NORVA that has a 4.0 and 1400 SAT, practically lives on the Yard and has wanted to go to USNA his entire life isn't the target audience, while that Midwest kid with strong academic performance and lesser SAT's scores, athletic and school leader who is barely aware of USNA . Both may apply, get appointed, and be great Midshipman, but USNA doesn't need to sell the sell the former on attending USNA.
One of the biggest drawbacks of the NASS program is that good candidates get turned off or feel that they are not wanted if they don't get accepted. Don't fall for that ---as '19 notes, there are many who aren't accepted , or don't go to NASS who get appointments, and many who attend NASS who decide its not for them. Bottom line, NASS is not a preliminary screen and not an indicator of success in the USNA Admission process.