Originally Posted by
Zorak
What matters is not the stock, nor who operates the flight, but the two letters that appear before the flight number on your itinerary as booked.
According to the DL
website:
Any eligible flight that is not Delta-marketed will earn miles according to these partner airline rules. For certain partners, earn will be determined based on marketing and ticketing carrier. [my highlighting]
So this does suggest the ticket carrier may matter.