They counted stuff like seats in their library.
And it is their rankings; what else did you expect? I'm just surprised they didn't end up #1.
That would've been too obvious. I love that they went up from #16 in 2007 to #12 in 08. More card catalogs in the library? A better cooler in the cafeteria? Or did they finally cave in and give everyone a lock for their locker?

It might be because they added more floor fans to the library to cool it down during the hot months.
I wish the link I have was still active. During another Cooley fun fest discussion on another law school board several years ago a guy made a web page about Cooley, their library as it is used to calculate their self designated rank and floor fans. It included charts and graphs and data from their own web page AND included pictures of inside their library taken over the course of over a year. Apparently somebody involved in making fun of them lived nearby and kept going in and snapping pictures.
One year during the super hot times only 2 floor fans were spotted. The next year during the same calendar weeks ~10 floor fans were spotted and photographed. Their self reported ranking was higher in the second of those 2 years and one of the rating categories they reported a much higher score for was library facilities!