Their consistent improvement on the criteria used for USNWR rankings (average ACT score and fraction of enrollees in top 10% of their HS class) confirms how their admission process works: very dominantly based on ACT/SAT scores and high school rank.
Fraction of students in top 10% of their HS class has improved from 61% for the class of 2018, to 62% for class of 2019, to 63% for class of 2020. Average ACT has a similar sequence: 28.8 for class of 2018, 28.9 for class of 2019, and 29.2 for class of 2020.