Enrollments rise and fall. In my time, schools like Burke, Battery Creek, North Charleston have been Class AAAA. I can give you all kinds of "cultural" reasons, but enrollments change -- sometimes, drastically.
Why? Population shifts, new schools and enrollment zones, etc.
As a cultural/familial matter, many Latino families and extended families tend to settle in certain neighborhoods and disproportionately populate the public schools in those areas. I'm thinking of schools like Stall, Brookland-Cayce, and to a certain extent, HHI. Personally, I think it's great that many schools are enjoying a new cultural diversity, and if that boosts their soccer capacity, GREAT!
I would point out that it's not a "given" that any random group of Latino kids will dominate HS soccer. I give you Goose Creek, where I have sat in the stands near their kids while their boys were playing, and heard as much Spanish as English. My point being, as good as you might THINK kids "should" be ... without coaching, administrative support and organization, it just doesn't happen.
Hence my theory about HH's success.