This is probably a dumb thing to say:
if we could really trace that much bot traffic to 3-4 big data centers, surely we could have already cut it off by filtering a few addresses?
Now, the obvious counterpoint, what if Russia has some massive distributed private network to disguise where the traffic is coming from?
surely that network is designed so it could handle a couple of nodes (in this case Data Centers) going out without us noticing a drop? Say Russia has 15 DCs, if 4 go out we should still be seeing ~70% of bot traffic