The more challenging the game, the more numbers I push out. Not sure why it would be in reverse for you. When playing a team of bads, you don't need to heal or damage for nearly as much because your team is not taking much damage and your opponent is dying off very quickly. The matches are usually quick as well.
Good players know to focus fire, know how to dogged pursuit you, keep you stunned and interrupted. Bad players can still do plenty of damage- they just don't bother trying to stop a healer.