Go to yobit BTC-WAVE, click on 7 day chart. See the grey columns? That means 50+ BTC "bought" at that point in time. Now look at the order book and riddle me this: how can you buy or sell 50+ BTC worth of WAVE in one go, without significantly moving the price up or down? That's proof enough for me. Same can be observed at LSK and ETH at yobit, by the way.

I have the suspicion, that the price dump at yobit is either initiated by yobit itself to revitalize actual trading, or by someone who wants to buy Waves elsewhere (probably here in the market section).