The 172K 4 steps away from the offer, 5 steps away from the bid,...

The 172K 4 steps away from the offer, 5 steps away from the bid, could well be the same person, but their orders are out of market. Perhaps they are implementing a liquidity provision strategy with a multi day horizon. Typical intra-day market making by the HFT people like Susquehanna would be somewhat tighter around the bid/offer than what you see here. 

Unrelated, the biggest net selling brokers of GXY over the past month or so, apart from Citi and DB, they are followed by 5 popular retail brokers. No retail brokers in the biggest net buyers list.