The article doesn't mention the grades and test scores of legacy students are as strong as non-legacy admitted students. "Among the admitted legacies, grades and test scores were indistinguishable from non-legacy students. Both groups had an average SAT score that surpassed 1430. Once on campus, legacy students tended to have slightly higher college grades, but their involvement in campus activities, merit awards, ac…
If you break down non-legacy cohorts where Asian applicants have to score 50-100 points higher, then academic performance of both legacy and non-legacy (average dragged down by AA) is artificially low.