US News actually abandoned the acceptance rate as a component of the ranking several years ago. They include % of entering class that is top 10% in HS as well as test scores, but as mentioned above, Duke probably has 5x the number of applicants that fit in the highest bands of those so could easily double class size without that impacting that component one iota. Where it WOULD impact the ranking criteria is "Financial Resources Per Student" which is worth 10%, and with more students, financial resources per student obviously goes down. So, my point is that admissions' selectivity is actually NOT really a component at all in ranking systems. The ranking is largely now a proxy for financials/resources (endowment size, how generous is financial aid, and then the all important "reputation survey" which basically is "prestige").
Here's the table of criteria:
https://www.usnews.com/education/bes...ia-and-weights
Graduation and Retention Rates: 22% (OADs pulling us down!! heeeeheee)
Social mobility: 5%
Graduation rate performance: 8%
Academic reputation (survey): 20%
Faculty resource: 20%
Student selectivity (test scores, 5%, top 10%: 2%): 7%
Financial resources per student: 10%
Alumni giving: 3%
Graduate indebtedness: 5%