Their new rear wing and new floor should make the car go quicker, but they do not have the track time at a race weekend to go through the thousands of combinations of ride heights and hard or soft suspension settings, versus high or lowwing levels.
Hamilton was on the third row not because the low downforce wing did not work but because he had made a couple of key errors on the lap, partly induced by being in the wake of Mark Webber's Red Bull.