Why is the price dropping?
Because there are more coins being sold on the market that coins bought right now.
i'd rather say: buyers know that others have been dumping for weeks and have been speeding up recently (probably to get all money out to jump on DRK) and do not "buy" (== drive the price upwards) since the dumpers will always deliver at a low price right now. Just look at the intervalls of orders being filled, could not be more obvious.