I was also surprised that Chen Jin lost to Jang although the time taken of more than 40 mins did not reflect the poor scores received by Chen. But here again, Jang lost to Sairul, who is a steady and experienced player but not quite of star quality, IMO.
Someone recently posted (kwun?) that China's chief coach, Li Yongbo, did not think that China's current youth squad comprising Chen Jin and co. is ready to take over from the seniors and probably he is right!
It would apprear that the Koreans are no pushovers, granted they are playing on home ground and without some of the better known stars of world badminton being represented, esp the senior Chinese team.