the graph nicely shows some general trends:
up to Barcelona the performance across the field closed ,indicating that all teams involved got more out of their package .
In Barcelona with the first big development steps suddenly the field spread out again with HRT loosing as much as 2%in performance towards RB .
For most other teams it was aloss as well but less pronounced.
For Montecarlo interestingly the performance curve of HRT showed a clear upward trend again ..so something has lifted their performance after Barcelona as the improvement is paralell for all cosworth cars in montecarlo I´d interpret this as an engine related item,either cosworth has found power .
the performance converged towards the europe race ...possibly indicating that this circuit is not very selective?
But then again a huge step by RedBull for the british Grand prix setting back almost the whole field by almost 2%..this might be as ign of just were RedBulls
real strengths are but in all it is apparent that both in Barcelona and Greatbritain RedBull has improved the car significantly.
so with alot of simplification we could say RedBull has improved by almost 4% since barcelona even if we give an allowance for both tracks suiting their layout
we still can conclude that we see at least 2% of net performance gain...