I don't know? Every single pool i look up. Is showing like 700+ workers.... every single one.... In early Dec the pools i was using only had like 10 and 25 .......those pools both now are 900+. I think there just really are alot of miners not just nice hash...
It's certainly something big and automated going on, this are not random human miners.

If you look at the various pool stats there sudden increases and decreases by the 100s of miners...

This can be seen simply by looking at the diff of the blocks. It changes not smoothly, but in a jerky manner, which indicates a sharp turn-on and the same sharp disconnection of capacities from the ITNS network.