It would be nice if any driver could be ironed out. Mistakes are usually a result of poor racecraft, and some drivers can not be taught that. Takuma Sato springs to mind, as does Vettel. SV and TS seem to be prone to mistakes in traffic more than they are prone to brilliance. At least Vettel still has a lot of time to prove his racing ability to us.
As many testers have proved (Wurz, De La Rosa, Piquet Jr, etc) raw pace can't always be turned into a great well rounded race driver, but it is a good place to start.