Sogdia is right. At UVa it is all about "fit," and relationships. It really helps to visit and/or to be in touch with the faculty throughout the process. For the administration it may be a numbers game, but for the faculty (who ultimately make the choices) it is not. Most people who are puzzled by the lack of writing sample requirement ask thier POI about it personally, to find out what thier preference is (some want it, others don't).