I'm not sure how Stephen King and J K Rowling rank in the traditional crime genre
The submissions or nominations relate to specific works.
Stephen King's was for "Mr Mercedes" and JK Rowling's (under the pseudonym Robert Galbraith) was for "The Silkworm". I assume they must have met the eligibility criteria (whatever they are) as I have not read either one of these books.
Ruth Rendell's book was "The Girl Next Door".
Other authors whose works were considered this year included well-known authors such as Kathy Reichs, Karin Slaughter, Tess Gerritsen, Peter Lovesey, Patricia Cornwell, Anthony Horowitz, Michael Connelly, Dean Koontz, Val McDermid etc.
If anyone is interested in the list of authors and the specific works considered, here is the link to the Awards list.http://thecwa.co.uk/the-daggers/categories/goldsboro-gold/