The title of this article says public high schools but they must be counting charter schools.
McAllen's entry says that its best high school is IDEA prep, which is a charter. It also says it has 31/60 in the top 25%, which is the only way you get an annoying number like 51.7%(rounded). But McAllen's MSA is just Hidalgo County which has 800,000 people and 60 would be too high a number of conventional public high schools in Texas. McAllen ISD itself just has 5 campuses, and 2 of those are magnet schools.
I think what's happening in the distribution of schools by enrollment heavily influences the ratio of high to low scoring ones. There are a handful of big public high schools with a large number of students with moderate scores and then a long tail small charter or magnet schools or early college or prep programs that get counted individually which have higher scores, probably because they are selective.
https://www.usnews.com/education/bes...allen-tx-32580
This makes me question this entire ranking as a proxy for general public education quality in any given metro area. The presence of charter schools and whether or not they are counted as public schools, or whether they exist as separate campuses or programs embedded in a school, would naturally vary by state and school district/city. I also think magnet schools would skew these rankings, if a school district runs a really big magnet schools like NYC's Stuyvesant for example, it still only counts as one school. Going the other way, if a school district runs an alternative school for troubled teens needing remedial classes that dings it unfairly. It goes without saying that a school system that tried to be egalitarian and put advanced programs or tracks into its normal campuses for its brighter students would also be penalized in this ranking. Nevermind that the whole concept of the top 25% gets thrown off if the "best" schools are largely selective small ones that identify as separate campuses.