lets face it, petrovs results have been crap, if he was a bigger name, like 'piquet' last year because of his dad, or if he had been a past GP2 or Champcar champion (like Bourdais), then more people would be on his back, but he is lucky in that he has come into f1, having never achieved anything, without anyone expecting too much of him (which is unfair to so many other drivers who are achieving outside F1, and cant even get into an crap F1 team like Virgin). In F1 you are only as good as your results, and at the moment he is not good, not good in qualifying, cant set up the car as well as his teammate, and is dreadfully slower then his teammate. seriously, watch the onboards of Kubica, then watch the onboards of Petrov, and you can really see the difference in skill between someone who can win in F1 and someone who is making up the numbers in F1 (even watch onboards of Kubica in his fist f1 races). you can see on the onboard videos, that Petrov is putting in a big effort, but he is so twitchy, puts on too much power with the throttle which loses traction and loses tenths of seconds, he cant put a perfect lap together ever, and Kubica does good laps, lap after lap after lap.
I know its only 4 races into his career, but he wont have a 10 year career in F1, he will be like any other pay driver, even the best pay drivers havent lasted.
Now there have been drivers that have been not the best at the start and improved immensely in their careers, ie Felipe Massa. But Massa was lucky to catch the eye of a team like Ferrari, which have helped his career grow. I dont think Petrov will ever get to such a position, its a very rare occurence in F1. He needs to perform just like all the other drivers, and at the moment he hasnt. Next few races will make or break his career. Good luck to him.