"his trip over the gravel" and "no damage to the car" suggests driver error.
I was watching a few testing videos yesterday on tube and it really hits home about how little we can actually learn about the "rankings" of the teams. You have a Force India taking it easy around the corners and then blasting down the straight with the DRS open on one lap, right behind them is a Williams riding the kurbs but not using DRS at all. Throw in the different tyres, fuel loads, it really makes establishing a rank incredibly difficult.
The only real info we can learn is how quickly a teams tyres drop off and at the moment the red bull looks to have the edge here. If you watch footage of the testing the most noticable thing that stood out to me was how "passive" and safe the cars are when taking corners, no one really seems to be attacking the circuit as such.