I'm here working in China and it's true. I know people here that trade BTC like I do and they've moved most of their funds out of BTCChina and into Chinese mutual stock funds. Their stocks are really hot now so it makes sense. Once their stocks stop popping they will be back.
besides that, the volume of cny is still huge, froo bitcoin(75%) and the global bitcoin volume is not reduced so much, but their slow exit, could be the reason for the dropping in price...