No offense to the honorable mention AAs, but the AVCA names about 50 of them. It's a huge club.
It sort of reminds me of how the NCAA names 'All-Americans' in Track and Field. It may have changed since the 90s, but when I was in school, I dated a high jumper, who ended up being an All-American. It turns out the top 8 'American' results/heights/times/etc. in each event are designated 'T&F All American status' for the season. So in theory if 15 runners from Kenya finish in the top 15 in the 10,000m, and 16-23 are Americans, those first 8 Americans are also AAs in the 10,000m. I think the girl I dated was actually 11th or something, thanks to the Canadian, or T&T jumpers from some other school.