They should have grown some balls, worked hard and actually used their talent. Lets be honest here Nalbandian aka burger king himself and Safin were never really that bothered with tennis. For all their talent they did not give a toss. Federer wanted success more and he changed before it was too late. Safin and Nalbandian did not change and they perished, Nalbandian more so.
To be fair, Fed was the only one who continued to change/improve his game over time from that generation (Hewitt/Roddick/Safin/Nalbandian). That's IMO what makes him so great, and not many can do that - recently, only Nadal and Djokovic has shown the same qualities - and the result is obvious.