As of right now, the criteria is:
#1: It has to be a title fight (major organizations only-IBF, WBO, WBA, WBC)
#2: The Mexican fighter has to have Mexican citizenship. If not, he's out. This is why you won't find Fernando Vargas in the list.
As long as it meets that, it HAS to be up on the list. The list has been here for several months and Chicano's modified it a hundred times with posters discussing and trying to find objective criteria as to whether or not a fight is counted or not counted. I think it's already well established what goes in and what goes out.