If there is a causality between OKCoin's problems and the current plunge in BTC price, then that would suggest that recent reports of China being the BIGGEST PLAYER in Bitcoinistan are true.
And it could be true! I have seen nothing that would tell me that US HODLers of BTC have been dumping them (although I recently spent some on gold).
Chinese bitcoin exchanges are the world's largest. This is no doubt about that, even if you discount their trading volume by 90% due to 0% trading fee.