Those low win rates do include some matches against horde premades. I haven’t tracked specifically how many are pug vs. pug or pug vs. premade, but since I mostly play on Sun/Mon (hoping to avoid people who are now bracket capped), I would say maybe 1 in 3 or 1 in 4 of my matches are against a horde premade.
That said, Alliance pugs are pretty bad in comparison to horde. I think most agree horde have on average the more dedicated and skilled player base (short of the Vampire Clan and Grizzly’s of the world).
In terms of the thread topic (AV), I will say that even when I was playing Rank 10 AV premades horde still beat us occasionally. Some may remember horde putting 30+ people on defense and basically dragging us out if our forward push failed (Pally pull got messed up, warmasters gone wrong, etc.)
Even in those days the horde pug win rate was much higher than the alliance pug win rate. Can’t blame them for trying hard with lengthy ques. Now that alliance have no hoping of winning, horde ques only seem to be getting longer and alliance who value honor per hour won’t do AV at all.