Van der Garde was a promising talent but he disappointed me this year, he was totally dominated by his team-mate Sergio Perez. In the first season half he was often getting in bottom top 8 in race 1 and therefore scoring big points for race 2 most of the time(thanks to the reversed grid). But later he totally sank, out of the points on his own or just getting bad luck.
Obviously if Virgin takes him it'll be mainly money based. I guess the 2nd drivers' talent doesn't matter much in the end for such a team, a good 1st driver should be enough to bring experience to the car's development and be there if there's an opportunity for points.