Remember that the higher Early Decision acceptance rate of 18% (7.3% Regular Decision) or 882 accepted includes the following “hooked” applicants:
100+ recruited athletes
400 “people of color” (URM)
32 Questbridge students
52 International students
584/882 = 66% of ED acceptances had a “hook”. A good guess is that if you are an “unhooked” applicant, your chances of getting into Duke ED is around 9%, only slightly better than RD.
It’s not the great benefit that the college tries to sell you or any other applicant.