I have read so many reporting and 'insider information' from so called China observers and experts, such as those about "all corruptors are caught as a result of Jiang-Hu power struggle". Such nonsense gradually faded when the notorious SFDA head Zheng was executed, as these observers could no longer trace the link to the alleged Jiang-Hu struggle.
A few days ago, there was another about the Minsiter of Treasury, Jin Renqing, alleging his demotion to be related to a careless leak about some casual remark form Wen. This, again, is absolute nonsense to anyone with a critical mind. The "Human Right Information Centre" really needs to be more scrupulous about its sources. Anyone with a sane mind would know the Chinese leadership are not primary school children as those informers to the "HRIC", who are into such kind of game.
Now, as the story unfolds, it confirms my theory of the story.
This is what I have speculated. There was a grace period given by the CCP to the corruptors, to admit their wrong-doing within a certain deadline. In return, they will be demoted or waived of prosecution according to the degree of their crimes. Most likely, Jin was one of those who confessed voluntarily. That was why he was only demoted. (yes, he moved from the head of a major ministry to become the deputy of a secondary ministry, DRC, the think tank. His new position was where the current head of Statistic Bureau Xie Fuzhan sat before he got promoted, and the Statistic Bureau is a less important ministry compared with the Ministry of Treasury)
The fact that he was "detained", was more likely a process for him to coooperate with the anti-corruption department, to provide evidence to prosecute the other corruptors. Chances are that, he would be released soon and be on his new position.