Silent Storm wrote:I never said its simple but the lower drag helps in laptime in Spa.
Yes, but lower downforce hinders it.
Again, the point is that there's an optimal drag and downforce combination for Spa. Shifting away from that optimum in any year makes your lap time slower. In 2010, they certainly were not deliberately moving themselves away from the optimum.
If the optimum is indeed (as you suggest) to run very little downforce and drag, then they would have done that in 2010 (as the rules allowed a 2015 like car back then, if you wanted to run it). The teams did not move to an extremely low downforce and drag setup back then, so the only valid assumption is that the higher downforce and drag combination was in fact better, not worse.
Remember, the rules have got more restrictive, not less. (Pretty much) anything you can do today, you could also do back then.
With that in mind, the only logical conclusion is that the improved engines is the reason for the improved performance, given that both tires and aero have regressed.