How is Gasquet underachiever? Or Roddick, Tsonga, Berdych, Denko...? I think they tried and did the best they could. Imo, the real underachievers would be those who could've tried harder/gave up too easily, but just couldn't be arsed. So someone like Gulbis, Tomic, Kyrgios, to some extent Dimitrov, probably Nalbandian too. Tipsarevic for the first half of his career/before 2011-12 too.