I did not believe and do not believe in bitcoin cash, it's just a speculative coin, Roger Ver paid alot for it, but so never made successful!!!
In terms of percentages BCH always outperforms BTC in a downtrend and in an uptrend, as well.
Trading volume / order book desnity and volatility are correlated - so this will change once usability & adoption gets higher by time.
Traders are loving high vola, though