I still think the fastest teams will be at the front, but teams that gamble say like Sauber did a few times last season, may stumble/chance into a better result more often.
It's always going to be the fastest teams and those that manage their tyres better than the rest that have an advantage, so I don't really think that much has changed.
From what I saw from testing, there didn't appear to be any one team that far outperformed any of the others, either in single lap or over a longer run. There were a couple of teams though that had better long run form than single lap form, but remember that testing doesn't involve traffic and having to actually pass people.