Well it's a model's duty to make the clothes look good so in the end blame falls on her. I agree that she looks thick around the waist. Losing an inch or two would help her significantly.
^In everyday life she's thin, but she's a little too large for fashion, which, although I hate to quote Tyra, "is all about extremes." She doesn't need to lose a LOT, but it would be good for her to lose maybe 5 to 10 pounds, or to do some toning.