Take a look at these payout addresses:
https://blockchain.info/address/1NLg3QJMsMQGM5KEUaEu5ADDmKQSLHwmyh

39 solved blocks in the last two days -> ~13% of all blocks -> ~13% of the hashrate:

5.8THash/s... that is quite a lot.

Does anybody know which pool/miner is that?