Belligerant: On the girls side, I've seen the "evenly divided versus A/B" thing happen a few times. In past years at least, I've also seen GA come in having practiced (not sure about other states -- but my guess is that they had not practiced).
Here's probably one of the biggest factors:
Not only does SC have a relatively small population compared to these other states, but it has an even smaller population of soccer players than you would expect even given the smaller population of the state, i.e., the deviation shows that our penetration of soccer into the state is abysmal.
