From my earlier post in this thread quoting from USNWR 2019’s publicly available explanation of changes to their rating system:
“Social mobility: New this year, we factored a school’s success at promoting social mobility by graduating students who received federal Pell Grants (those typically coming from households whose family incomes are less than $50,000 annually, though most Pell Grant money goes to students with a total family income below $20,000). See below the two measures that factor into social mobility.”
https://www.usnews.com/education/best-colleges/articles/how-us-news-calculated-the-rankings
"New for 2019, acceptance rate (1.25 percent in last year’s ranking) has been completely removed from the ranking calculations to make room for the new social mobility indicators.
Also, we reduced the weight of the two remaining student excellence factors assessing the fall 2017 entering class – standardized tests and high school class standing."
https://www.usnews.com/education/best-colleges/articles/how-us-news-calculated-the-rankings
Are you sure you’re getting your information from the 2019 (most recent) version?