I think black magic (or FM) is the best way to describe how things work. Not only is your NSS important, but whether or not the skipper recommends you for a tactical community, if you're married or single, and other off-the-wall categories. It all boils down to how well you will likely do in a certain pipeline. The NSS plays a large, but not sole, part to this.
Now point of clarification please: does API/Academics count? I have heard both ways. I first thought that it does not, but on the forms for the NSS there are spots for API and the Primary academics.