I rate it based on the amount of overtakes and how excited I felt about the race in general that's why I gave Azerbaijan a 8 or 9, my highest rating this season I think. I didn't give Azerbaijan a 10, because it had too many incidents which unlike the 2011 Canadian GP were quite annoying.
I don't base it on any drivers performance, a) because I don't really have a favourite driver, except Palmer and b) because I interpret the purpose of the rating differently.
This race was given a 7 out of 10 rating, because it had some nice overtakes at the beginning, a chance of a battle between Vettel and Hamilton, certainly after the SC, and the incident between the Force India drivers which caused the field to bunch up again.
Well, if it has already been discussed... case closed.