Delta has confusing language on their website regarding earning MQMs on delta partner flights. As of March 1st, they state that the new MQM chart applies for partner tickets flown on or after that date. (But, for actual delta flights, its based on ticket purchase date, not flown date)

HOWEVER, upon multiple phone calls to delta, an agent confirmed 100% that my flight purchased in January but to be flown this coming May on Korean Air Prestige Class (Fare class I) will earn 125% MQMs, not 75% MQMs as listed in the new chart. He had talked to the skymiles department to confirm.

That said, it's based on partner tickets purchased on or after March 1, not Flown. Delta should update it's website and train its staff. I received conflicting info on this from multiple sources!