YMMV - but I did my audit. Fortunately for me only 40 segments to check and cross check against what was paid. Of this, I'm missing what I believe to be just under $2k in MQD that I should have been credited based on what I paid for, got ticketed as, and flew. (Taking into account only the base fare of course, no other fees/charges). That's >10% of the MQD needs for a DM which seems more than just an error. FWIW it wasn't only affecting tickets that got changed - some tickets just didn't post correctly at all. There seems to be no rhyme or reason. Equally, on tickets that got changed, and ended up with an ecredit, i.e. actual flown MQD earning was less than what was originally ticketed - and those ones got posted correctly, so it's strange that some of the tickets that later got changed to more expensive fares, remained posting at the originally ticketed value. Note - the 'I paid x for the ticket, then changed to a more expensive y option and only got MQD credit based on x' didn't happen on all of my changed tickets - just on some. Again no rhyme nor reason. Just emailed them to fix it. Don't much mind if it takes them till the new year, I'm sure they'll retrospectively apply if my numbers are right.

Next thing, separate issue - why don't they accrue ALL spend with Delta against MQD requirement? I pay for SkyClub access, this is dollars to Delta. I pay excess bag charges sometimes. I pay WiFi fees. All told, this amounts to about $2k a year in extra spend. Seems silly they don't factor this in overall business value of the passenger. Maybe too tricky to track it all?