The only really decent and top 100 player that Duan has defeated in the last 12 months is Kimiko Date-Krumm, and that does not bode well for a player ranked just outside the top 100 herself. I have no problem with her being 150 or 170 in the world, but a player with such mediocre wins has no business being in grand slam main draws unless she gets a wild card or qualifies - she should not be ranked high enough to get direct entry. But Duan has never entered Wimbledon or Roland Garros qualies, and has never played in Europe since her dismal ITF sequence in 2007. You cannot argue that she deserves her place in Wimbledon more than someone like Petra Martic, for instance.
Whybourn is no great shakes but she is no worse than many MD wild card level players from Australia for instance.