if some wicked and low skilled kids place a lot of landmines and those guys are spotting them and defuse some of them they gain xp... doing obj as eng/blowing things as covert ops and frags provide to gain such xp and ppm...
skill, knowladge of game and lowskilled retards nothing special to do sth like this.
look at average ppms and rating of rest players during ranking session that's all.