A fuzzy rank, is a term used to refer to an informal pseudoscience, by which people estimate their rank via a detailed and documented statistical analysis --using fuzzy logic to grade the truth states of a persons actual rank relative to their claimed rank.
So for example, if Billy Bob says that he is a 3k, we can generally estimate that he is anywhere from 5k to 1k - which would depend upon the persons character and moral grounding?. To assign a truth state to the persons rank, a relative rank matrix? must be constructed --the more populous the data, the more accurate the ranks therin will be described. Games then must be tested and analyzed. Here is a scenario:
Billy Bob plays James Vanderkrumpnikhillson, who is a notorious Shodan tickler, and wins. Because the ST's rank in indeterminable, like the speed or position of an atomic particle, the win is useless for Bob's rank. Without a prior win with a bonafidely ranked individual, a win against JamesVanderkrumpnikhillson will perpetually doom BillyBob to the fuzzy rank of an ST.