If I had to guess I'd say that date of rank will still reign supreme for pin on dates so that would solve most of the pin on rank order across the categories. I would be really surprised if they apply merit based order the entire list and suspect that it will just be a few top performers that get bumped to the front of the line. Also keep in mind that the 06 year group is in an interesting place this board. Our "best and brightest" would already have been picked up BPZ during the last two boards, so who would they be pushing to the front this time around anyway? IDE in-res grads? Those who just missed the cut BPZ last time around? I think rank order will become more of a factor in future years with year groups that didn't have the opportunity to have their best promoted BPZ.
I also want to add that I recognize it's not always the best and brightest who make it BPZ and that not all of those who are truly the best make it BPZ.
As far as the delay goes, it's hard to tell if there even is a delay beyond what could be expected when a lot of people working the process are probably teleworking. With updates being announced over a month after they happened (looking at you 22 July SECAF date posted in late August), who knows where it really is. While it's fun to be the guy "in the know," rumint is just that, rumors.