ca2midwestmom,
I don't know for certain what my LOA is "for", but if I had to guess I would say academics. I am not particularly diverse in any sense of the word, and while I intend to try out for the Club Water Polo if I eventually get an appointment, I have not been recruited for either of the sports I play in high school. I am also a HS senior and a first time applicant.
I copied and pasted this stat list from one in August so it is not 100% indicative of my current stats. I was named co-captain of my HS varsity swim team and elected Vice President of the Math Tutoring club which I previously mentioned. I had my counselor email these updates to USNA and I feel that this gave me a large amount of points in the "Leadership" section of the application.
Also, I had my counselor verify that I was in fact officially a National Merit Semifinalist, and I paid to have my AP test scores sent to USNA. I know they are not required, but I got some advice that they would help strengthen my file (I have scored five 5's and one 4 so far, with a 5 in Calc AB and a 4 in Chem). Supposedly this helped indicate my preparedness for USNA's academic courseload.
My CFA was okay. I maxed out push-ups and sit-ups and did well above average on pull-ups (15). My run and BB throw were around average, and my shuttle run wasn't very good.
The fact that my state (MO) is only middle-of-the-road regarding competitiveness probably helped too.
I also had everything but the BGO interview in before the end of September. The physical interview was done by then, but my BGO did not submit it until mid October, and I got a call around the beginning of November stating I was to be given an LOA.