Getting an MBA is a 100,000 + investment, applicants put so much emphasis on rankings and hardly a handful even take a look at how they work, the strengths and weaknesses of each and the variables involved.
I cringe when I read someone saying X is better than A because BW says so, or USNews or Forbes.
Student satisfaction is a biggie on some of these rankings - some top schools get penalized because their students arrive with higher expectations, and although they end up getting job offers with higher starting salaries, more prestigious companies come to interview to campus and have a higher % of job placement at graduation.. these schools still receive lower marks because some students at not such top notch schools went with lower expectations and were pleasantly surprised with the job they ended up getting.
Recruits assessment is also a biggie, some smaller programs / located in isolated towns get penalized. These school might not be on top of mind for some companies. Being in a a smaller class with more interaction with professors and having the opportunity to focus more on your studies could mean that you will be much better prepared to go out into the job market and with some self initiative you can land an awesome job in a company that doesn't recruit on campus. Some companies simply don't go out of the way to an isolated school with a small class to recruit there, although they might have amazing students, which doesn't mean they wouldn't hire them if they decide to make the trek to interview in NYC/Boston.
As the previous poster mentioned - starting salary could be the best indicator - if you were to choose one of all factors. Since business school use one common denominator to compare us - the GMAT - I use starting salary, but as you know its a "holistic" approach, so other factors come into play.