Chanel explained the choice in a near-incomprehensible statement to WWD:
Lagerfeld had a crush on this unique, charismatic young lady, who is both a model and musician, during a photo shoot several months ago. This previously unforeseen alliance finally became self-evident. Alice Dellal represents the perfect incarnation of all that is unique about the Boy Chanel handbag collection, which strives [to be] far from conformist notions of femininity.
In short: Karl liked her. He really, really liked her, enough to photograph her for the campaign himself. In a preview image released to the industry paper, Dellal sits on a desk in an antique-furnished apartment, dressed in a white chanel dress and clutching a grey handbag.More