I don't think we can say with much certainty why we got the award and others didn't. For what it's worth, I had a pretty good GPA (coming out of undergrad) and GRE scores, as well as a research topic that could have broad impacts across several DoD-related fields. Also a fair amount of practical design work in the aerospace field, though only a year of real research (first and second author on two conference papers). Very little community service or extra stuff like that, and I didn't spend much time actually doing the application/essay; about two days total.