I think a a lot of factors are in play but Charlotte has grown so much in the last 20 years it's hard to find someone actually born in NC anymore and that dilutes the local fanbases in general.
Then states like SC and WV are small enough there are limited job opportunities for college graduates so a lot of SCAR, Clemson and WVU grads end up here for work.
With UNCC adding dorms, football, etc., it isn't seen as a glorified community college/night school anymore. And its enrollment has grown to where they are as big as UNC.