Yes, it is based almost totally off win-loss record. They tally them themselves from the big leagues, but if your an indy guy, your fed or yourself has to send in results that they tally.
A couple years ago there were a bunch of people listed from a small fed here in Quebec just because they sent in results. Practically no one outside of Montreal even knows of the fed, practically none of the wrestlers that were listed had even wrestled outside of the fed EVER... It's a total crock of shit and pretty worthless as a ranking system, since well, you know, wrestling is rigged.