Well on the last game I played, top and mid were pretty much going even, and bot lane had a bit of an advantage over the enemy. It eventually led to a fight at dragon pit and we got first dragon, and from there everyone in the team snowballed so hard that it was just one turret after another and eventually their nexus...I think that dragon ≠ auto-win, but for any team that knows to prioritize objectives, snowballing would be easier than last season.
Now that I think about it, it was also perhaps because our WW did spend a lot of time getting that crab on the rivers. I don't think the enemy team ever did get a dragon, as we took 3 or so.