NA is (or at least was when I played) the most populated and visible regional zone, and attracts a lot of players attempting various kinds of rank manipulation. On the one hand you have smurfing, which is the practice of a relatively high skill player using a an account with relatively low rank so that they can dominate lower ranked players. On the other side you have boosting, which is a relatively high skill player ranking up new accounts for later sale.

In practice this means at lower ranks, it was not at all uncommon to be matched with players with similar rank but vastly better skills.