It takes a bit of work on the TA and Disney's part, but yes, a TA booking CAN be eligible for an upgrade. A good Disney TA can "make" the WDTC go through guest records to search for a possible offer. This is a typical Disney pin code offer, and the offer must be associated with the guest's name/address/phone number. These offers have not just been sent to folks who are already booked and according to my rep today (a long time CM who is very good) there have been postcards mailed as well as the emails. According to my info from Disney this is an offer straight from the Marketing department. It is random and totally miscellaneous--without any rhyme, reason, or logic. There are some things that the TA needs to ask for the Disney rep to check. It is definitely not a quick process and a CM needs to make an effort to check many things to find the potential upgrade.
The dates for the pin offer are only August 26-Sept 1. This is a very, very small group of guests. Also, the resorts in question (OKW and SSR) have a limited number of rooms available and once they're full, they're full.
What I suspect happened is that the Values are totally full, but there is still availability at the Mods and Deluxes. Disney wants to move folks from the very full Value resorts into the lower occupied resorts in order to free up more rooms to bring in more people rather than have those rooms at OKW/SSR remaining empty. Just my opinion of course, there there are still Mods available from Aug 26 on, which really surprised me.