I don't think Na'Vi is a bad pro team, but I think on their glory days, they were 1 or 2 steps ahead of the opposition. Like a seasoned veteran playing among kids.
They didn't only win, but did it with such a dominance performance you would think the enemy team had no chance. Beating Na'Vi would instantly bring a no-name team to the spotlight.
But now I feel every team learned the basics. You can't mess around on the early game or do crazy dives and expect to go unpunished. Plus a new patch give the teams a fresh start as old heroes and tactics phase out.
I expect them to win a lot, but I won't bet my rares blindly on them.