Germany was totally outplayed, but Germany doesn't spare you if you make dumb mistakes no matter if it's A, B or 10 years old playing for them.
Chile created a lot of chances but was unable to score and had an awful defence.
So both hyperbolic reactions (OMG! Germany B beat you / OMG! how pathetic was that win) are unwarranted.
The German B-team might be worse than Chile's full squad, but they executed their strategy perfectly and came away with the win. You can't really say they got out played when they played the game they wanted to, how they wanted to do it.