Patek dress watch models trading well below retail?

Is there any particular way to understand why some prominent dress watch complication and grand complication models, including discontinued models, have been selling well below retail price?

For example, the 5960 is the original annual calendar with a flyback chronograph, and the flyback makes it more complicated than the successor 5905, regardless of one’s preference regarding the face. This watch has been trending down to about half of last retail, and the 5960P is just slightly higher than gold models based on Watch Charts.

The 5270 is much cheaper and much lower below retail than the predecessor 5970, and the 5270P in particular is much lower relative to the 5970P. These are the flagship perpetual chronographs, separate from what one thinks of their aesthetic.

I’d love to get another Patek non-Calatrava dress watch, so any advice on navigating the pricing of these, especially discontinued models?