Two years of domination and no large rule changes will do that to you though...
Indeed.
Some people appear to have forgotten just what RBR achieved last year (ie. one of the most dominant seasons, by a single driver). They don't seem to be aware of how good RBR (as a team) are. They are in absolutely top form and even if you gave other teams an advantage (eg more testing time), my money would still be on RBR, if only because they are the best team in F1.
If we were starting from square one, all teams level and RBR were not the best team in the World, then I would absolutely agree that 4 days of testing can in no way, be used as an indication of the ultimate speed of the RBR.
What is worrying was that Webber, on Tuesday was unbelievably consistent in his (fast) lap times. This means that he has a car which is easy to drive.
It is likely that RBR will start Race1 with the best car,
however, it is possible (as we saw last year, with McLaren) that another team may change some key features of their car, from now till Race1 and may gain an extra second/lap. I'm hoping that this other team will be Ferrari or McLaren, because I desperately want to avoid another season of seeing Vettel winning races with ease.
What I will say is that we should not be looking at the absolute lap times being set, but more the regularity and ease with which the team is posting that particular lap time.