Billy Owens, he said so himself. Before his heart condition slowed him down, as good as he was, DC was viewed as being lazy. Karl Malone at one point said he could be the best power forward ever, if wanted it. Donte Greene. Dion.
In contrast to that, less talented players have carved out great careers. Sherm did well considering how undersized he was. Jason Hart probably had a longer career than almost anyone could have anticipated. John Wallace, Etan Thomas, and Hakim Warrick probably maxed out their potential. Jerami Grant is having a good career.