Yea the same guy with an fpga farm in china mines pretty much every x11/x13 coin like that for the past few months.
Ocminer, it's not a bug.
He let's the hashrate drop, then when the diff is low he pumps a shit ton of hashrate at the coin in an effort to grind through a bunch of low diff blocks as fast as possible.
Then he dumps his hashrate onto another coin and let's the other miners solve the high diff blocks till the diff drops back down to as low as possible.
Rinse and repeat.