Not trying to be argumentative because I think we are all fans of the show, or at least interested.
Sundance Channel has what the industry calls 'interstitials' during act breaks in episodes promoting their own programming instead of commercials. Much of their programming has one major sponsor that covers the arc of the series season. For example if a car manufacturer is the sponsor of an environmental show, there might be an interstitial about the manufacturer's green policies but never an advertisement for the product itself. That is how the network is able to produce their own programming.
Sundance definitely knows who is watching their shows and that is why they approved and put more money into producing a season-ending special but they do not have traditional ratings that are published.
If you're sure you've seen numbers, please share. Otherwise, it's misleading to say BGJW 'was in the bottom quarter of Sundance ratings and not improving'.