Note that this is not a complaint about the way that it's supposed to work but it appears to me that something isn't working correctly. I thought that I understood the way that Delta prioritizes the complimentary domestic upgrades for Medallions (with the exception of full Y which get upgraded right away). At the appropriate window (DM, PM, GM, FO) upgrades clear (as available) in declining Medallion status order with fare basis as the next deciding factor (YBMHQKLUT awards). Some tie breakers are Million Miler status, AMEX Reserve, time upgrade requested / ticket purchased and maybe others. Now, the "funny" part - my partner and I (both PMs) frequently travel together. I've noticed that he is almost ahead of me (by one person) in the upgrade waitlist (assuming that we didn't clear at the window of course). Sometimes we are on the same PNR and sometimes not. I'm a Million Miler and he's not. We both have the Plat AMEX (individually and separately). My SkyMiles number is lower than his. Alphabetically, my name is before (both first and last). My current balance in the account is greater than his. The glaring example was this past Mon on CVG-DTW (not that it really matters but it was just strange), he was 1 above me on the upgrade waitlist as usual. For this trip we were on separate PNRs, fare basis was the same (both coach awards), my ticket was issued a few days before his, I checked in before him (since he was a possible cancellation until just before the trip). Given all these factors, and the differences in our accounts, I should have been above him in the upgrade waitlist. Something isn't working right with Delta's computers.