Chen/Jia is current world #1, most dominant pair last year and just coming from the best year in their career. I agree that they lost back to back to a much lower opponents is an upset. Some of the posters here are heavily invested into Japanese badminton scene and they will say that we shouldn't surprise at all. This pair could beat anyone etc2, but it is more about their style that don't suit Chen/Jia. Polii/Rahayu beat them with relative ease, granted that Polii/Rahayu play better nowadays. Let say it's comparable if Kidambi beat Momota twice in a row. Both are ranked #1 vs #12, everyone will have pikachu shocked face.