Ranking systems for universities and colleges are a rich topic for discussion, especially in the United States. Read my previous blog posts on the subject here and here for my pretty non-radical take.
For an illuminating approach to the topic, from a very adept source
Ranking and assessment assume that a college or a university is good when it can promise, in four years, to turn out a student who is a certain kind of well-functioning product. But students are not products: they are people who are evolving into citizens, workers and neighbors. Thus, students and their parents should not be comparing schools to each other. The correct comparison is to match up what the school offers with what the student herself thinks she wants. (Emphasis mine)
Despite the U.S.-centric perspective, this is one of the most blogworthy statements one could make about the disconnect between rankings and learning.