The CW doesn't require the same size audience that other networks do - and it sells to streaming (exclusive to Netflix apparently). It's not available on demand or hulu, which is interesting.

My guess - is the nitch audience it's going after loves the shows and is less picky? I know a lot of folks on DW who love these shows, see them as thoughtless guilty pleasure television. So, that may explain it. (shrugs) They also appear to build on their relationships over time.