I think ASIC manufactures is hidden mining ETH and other Ethash algo.
Last day ago, ASIC manufactures announce ASIC for Cryptonight algo, this is KILL GPU miners.
Before they announce new ASIC, they are using this ASIC,
They have been for quite a while, they are keeping it hidden like you said. They only unveiled it cause they want to buy eth cheap and before they unveiled, they sold most of their eth while it was high and then are buying now as eth crashed 4 times its highest hit value.