Don't think you have painted an accurate picture by drawing out only two transactions to compare.
Jun 08 at $590psf is unit #10-09, this is the same unit that transacted at in March for $885psf. The seller who sold it lost $340,360 within 3 months. There could be a host of reasons why it was sold so low and we may never know.
On the other side of the penny, the rest of the subsales in 2008 transacted above $800psf, with the exception of the May 08 transaction at $798psf for unit #02-01, I suspect that has to do with it being locatin in the lower level than any other reasons.
Overall, most of the subsellers earned a profit around the region of $200k +-.
May not be right to claim the market is down because of one transaction.