I think the variance has increased greatly with the ARena patch. I've had a couple drafts that were basically old Arena decks, thanks to the spells being offered being crap.

And then there's my current Priest deck, which managed to get a Dragon sub-theme going and has the following AoE:

1x Excavated Evil
2x Holy Nova
3x Dragonfire Potion
1x Chillmaw


And I also passed up the Murloc that AoEs.

So um...yeah. Blowouts at low wins are going to be much more common now, I think. And high win Arena is going to be insane.