The current FCM system was put in place in May 2017. Prior to that, FCM offers were not available on award tickets (and I rarely saw offers available on my typical cheap X/V fares) and fare diff or booking class seemed to be a factor in pricing. With the new system, it's seems pretty clear they have a number fixed priced points on each route and the fare diff/booking class is no longer a factor. If you are trying to search for some pattern for offers based on your original purchase price/fare difference, I suspect that will be a fruitless exercise. The goal is revenue maximization, not necessarily the most logical/rational system. It's similar to how airlines will often charge more for flying A-B, than A-B-C (which also causes quite a few people scratch their heads). There's probably also still some bugs in the system. I believe high pricing on domestic segs of international tickets has been observed a number of times and is most likely not intentional.

Quick update: 17 F seats open at T-24. The entire upgrade list of 15 cleared at like T-12, leaving 2 open seats (and the FCM offer disappeared). I guess FCM being the death of complimentary upgrades is somewhat exaggerated.

what are these routes where something below diamond gets upgraded?

There are some strange algorithms that RM puts in place.
I flew DCA-LGA-DFW on Friday and both upgrades to FC cleared for me at the DM window. (award ticket)
I'm waiting to see what happens for my next flights - DFW-ATL-SEA 9/22. The app shows DFW-ATL with 7 and ATL-SEA with 5 seats (on a 333). No price for FCM DFW-ATL (which may be because the upgrades are processing now) but ATL-SEA is $767. I could buy a 1 way FC ticket for $604 (but $1335 on the flight I'm booked on). For some strange reason the ticket only cost me 8,000 miles.

Sad, because DFW-SEA was an announced new route on a 220 before Covid.

SFO-JFK. Obviously the entire upgrade list clearing is an oddity of the pandemic – lots of leisure travelers and few business/frequent travelers. But I'm surprised at how high the FCM offer was, given how many seats were available. You'd think Delta could have sold at least a few of those 17 seats with a more reasonable offer.

Interesting. I recently went SFO-ATL-RIC and only 1 diamond got upgraded, and there were 4 on the plane, none of the platinums of which there were like 35 got upgraded. On the way out same story as far as the rank it took to get upgraded, but there were 3 upgrades (all diamonds). I guess I should start preferencing routes that dont go through ATL.

I'd guess it's a few different factors working together. JFK/SFO is a highly competitive route with nonstops on 5 airlines vs. ATL/SFO which is only served by Delta. JFK/SFO is mostly origin/destination traffic that's going to be hit especially hard by the drop-off in business travel. Frequent flyers are going to be split across all of the airlines in SFO and NYC, whereas flights to/thru ATL are going to be mostly Delta elites.

Try a 9pm MSP-SFO when they put a 757 on it. Out with seven empty, and of course the FCM was $349+.

As a Platinum Medallion, I've been flying JFK-LAX monthly since being vaccinated in May. Only once was I even close to getting a complimentary upgrade, with most flights ending up somewhere between 7 and 17 on the list. I've requalified and have the Reserve Amex, so I suspect most above me are DM. I'm very surprised to hear your position about SFO-JFK being a different route. I take my first flight on Monday the 27th, so I guess we'll find out. At the moment I see 12 open F seats, but I often see the same for LAX and there is maybe one or two available for upgrade come flight time.

Regarding the FCM, I too have been baffled by the same pricing. $965.35 seems to be the magic number despite a new one-way being priced at $800. What gives? Thankfully I snagged a cheap Delta One return back from LAX next week @ $650 for the one way on the 11:59pm red-eye. All the other flights were $1,400. Interesting algorithms going on...

My SFO return was at 11pm, still packed :(

Shame is my local airport can only go to hubs, but I guess I can at least try one of the lesser hubs like DTW or JFK or MSP from now on.

SFO/DTW upgrades aren't always easy to get either. I use to fly DTW/SFO a few times a year pre covid. There were times I would clear on a DTW/SFO afternoon flight at the window and times I would be number three on the SFo/DTW redeye as a diamond with a waitlisted RUC. I don't remember ever clearing on that route when I was a PM

Don't forget on those D1 routes such as LAX/SFO-JFK it is likely there are some pax using RUCs which will put them above comp upgrades.

But I also frequently see the FCM offer higher than the straight up discounted F fare.

BWI-DTW-ICN, departing on 9-24 (tomorrow)

Purchased Comfort+/Premium Select tickets in W/G as a relatively new gold. No upgrades offered on BWI-DTW leg. DTW-ICN leg had a D1 offer for $1977 for the past two weeks until today. Offer was $599 for the leg today, which I paid.

Hoping for something similar on the ICN-DTW leg (currently at $1882) on the return trip.

Agreed on this. I have taken a bunch of JFK-LAX flights the past few months. I've never seen less than a minimum of 20 names on the upgrade list and I've seen as high as 40. And it seems like generally there are 3ish D1 seats are available day of the flight. And that's both directions.

And not sure it's based on the time of day. The last Sunday 7am flight I took to LAX there were 30+ people on the upgrade list so even atypical business times have had a lengthy list.