See I have been thinking about this whole "the rest of the world isn't playing that well" but I am not sure it's just that (or even that it's the biggest factor). I think the AB's play at such tempo (Faster than the AB's of the Mccaw Era even) and with such accuracy that teams just can't keep up. I can't recall the last time the AB's had a "bad" game. I recall a few years ago, usually, the first 3 tests of the year where most fans had their head in their hands lamenting school-boy handling errors etc. This year we have pretty much been on point with our handling. Obviously, it's not possible for 100% of passes to go to hand when you are throwing as many passes at the speed they are currently going, but it's pretty freaking impressive.
The Walleroo's didn't really play that badly, the Black Ferns just played SO well. I don't think any team could have stopped them. Our runners are faster, our ball barries are stronger and our breakdown clearouts were really accurate.