Even in the core MM, most of the humanoids (orcs, goblins, etc.) are presented as 1st level warriors. MM IV takes it to the next step and presents them as they would actually be fond "in the wild", so to speak. For instance, if you re-wrote MM I today, the stock goblin might be a 1st level rogue, with a 3rd level fighter/rogue chieftain and a 3rd-level wizard as a shaman, and the racial info there to let you build whatever you want. The assumption in that entry is that the off the shelf goblin tribe has those guys in it.