I don't think Del Potro is, he's just been injured a lot. My point was more about their ability to challenge the best players in granslams etc, I just think they have a better chance than Ferrer, I agree he's solid and has made the best of what he has, but what he lacks is what means he'll never be up there with the top players. The likes of Del Potro, Berdych and Soderling can and in some cases have, sadly injuries and health issues have stopped them doing so.