This sort of thing just shows that the art of producing a good cover lies in getting every aspect of it right - a mastery of proportion and space, conveying excitement in the coverlines, ensuring a sense of 'life' in the face of the model on the front, selecting an eye-catching colour scheme, and having a strong feel of the overall fantasy that's being sold.
Whoever makes the final call with their covers seems to have a theoretical understanding of what should make a good cover, but no true natural instinct for producing them on a regular basis.