I only watched her 1st round match against Bovina. She played well, but partially due to weak opponent - Bovina, who was as high as #14 at one time but now at #9xx probably due to injury in the past 2 yrs. She lost to Hantuchova yesterday, but I didn't watch that match. The stats on sina said she lost 6 serving games, which by any means is no good.
Consistency, movement, and serve are 3 top areas she has to improve to get to the next level, IMHO.
Regarding Chang, I think he might get better result if working w/Li Na. But Peng Shuai is younger and therefore might have more potential. But I heard the real reason Chang working with Peng is Tennis Asso. of TJ paid and invited Chang while the Natioanl Tennis Asso. is reluctant to do so. oh well.