Echoing Time2. We tell folks over and over again that NASS is primarily a recruiting tool. Folks from geographic areas, schools and demographics that have historically been underrepresented at USNA have a much better chance at being accepted than does someone from Annapolis, MD. Thus, being turned down for NASS is not necessarily any indication of whether or not your application to USNA will be successful.
The converse is also true. The fact you were accepted to NASS does not necessarily mean you're a competitive candidate for USNA. In many cases, you are. In some cases, you're not. Every year, some folks turned down for NASS are admitted to USNA and some folks accepted to NASS are turned down for USNA.
Whether or not you were accepted to/attended NASS, if you want to attend USNA, you need to apply. You need to give your entire application, including the MOC application process, your best effort. And then you see how it turns out.