I would be interested to see their definition of "all other credentials equal". My assumption is that it is some very simplistic compilation of grades and test

I would be interested to see their definition of "all other credentials equal". My assumption is that it is some very simplistic compilation of grades and test scores, because the article barely mentions any factors other than these. Also, many of the things that drive college admission are not easy to objectively compare - is a great cellist equal to an 3 sport letterman who was also on student council? How does a rich kid whose parents send him to math camp compare to a kid who had to work full time during the summer? And so on.