I think that the problem with Nasr is the wrong decisions he made. Of course, it's easy to judge now. He couldn't know where his decisions would take him. He stormed the field on the Formula BMW and even more on the British Formula 3, on Carlin, having Magnussen as a teammate, for example, which landed on McLaren soon after. By that time, Nasr refused to sign a contract with Red Bull's junior programme, so he wouldn't close doors on other teams in F1. So he decided to sign with Button's and Raikkonen's manager, Steve Robertson.
Then Nasr landed on the car nº2 on Dams for his first season on GP2, all eyes on him. Things went wrong, the team screwed him up a few times (a loose throttle wire in a race, for example), and even though he was the second best rookie of that year. He probably though that things wouldn't work for him at Dams, so he got back to Carlin, where he knew some people and felt at home. Carlin is the best team in the British F3, but they usually suck at GP2. Even though, Nasr managed to push the team up on the ranks, and even fought for the title.
So, yeah, Nasr didn't showed on GP2 the results he had on F-BMW and F3, but the potential is there. Van dere Garde is 29 already, FFS. If he had any potential, he would be there on the grid. So, let the young kids show what they can do. Max has the potential to bring joy to the dutch people. Van der Garde, no.
