Maybe Marloes didn't casted because of her walk . I never seen her walk but I've heard some people say on tfs best/worst catwalk thread a couple of times that her walk was not one of the best. So maybe that could be the reason. I mean people say that was the main reason Sara didn't get casted last year.
Although Vs has casted plenty of models with jank walks before and even has an contracted angels with a not so good walk so..... unless it was for another reason
VS just make odd/out of the blue choices sometimes especially when it comes to the casting for the show. Till this day I still don't understand how girls like (no offense) Maud , Dorothea, Anja, est can make the show yet they want give girls like Cintia the time or day.