P:NW's numbers are just under what the Monday scripted shows got. Which is surprising given the Sat timeslot. But those Saturday night movies typically get close to 2 million viewers. It's a wonder the network left both shows there as long as they did.
And there you have the real problem. People are always blaming the networks for cancelling the good shows and airing the schlock, but the fact is, the schlock gets a much huger audience than the good stuff. Mindlessness is what the majority of television viewers want. And any network dependent on ratings and ad revenues to stay in business is trapped by that.
But the ratings on Syfy have nothing to do with whether or not R:NW or Sinbad got renewed or cancelled either for that matter. Syfy has both series now and can air them as they like as long as they have the rights to the shows, they seem to have brought some older shows recently in marathons like Highlander.