I think that works by both Williams and Miller pick up on some general themes of modernism. The most elemental is that their works depict characters who are fighting against social orders that are either outwardly against them or represent values that are antithetical to them. For Williams, this comes out in a variety of forms. Characters like Blanche from "A Streetcar Named Desire" or Tom or Amanda from "The Glass Menagerie" in Williams' work or Willy from "Death of a Salesman" or John Proctor from "The Crucible" all represent individuals who are poised against the social order. These characters connect to the modernist theme of alienation, or not fitting in with one's social surroundings. At the same time, I think that a strong case can be made for these characters also being somewhat afraid of the world in which they live, that the world has progressed and left them in the dust. As social orders march towards advancement, individuals, specific individuals, are left as casualties. Works by Miller and Williams focus on this modernist idea. Blanche or Willy are prime examples of individuals who cannot seem to not only find success but fail to understand a modern setting's criteria for it.