From a PAYING passenger's perspective here's why Delta is successfully competing with Alaska:
1. Unless you're going to the West Coast, Delta has more options to anywhere else in the U.S.
2. The cabin service is similar.
3. The cabin amenities are similar.
4. The Delta Sky Clubs are superior.
5. Alaska has ZERO organic international options outside of Mexico and Canada.
6. Widebody aircraft are more passenger friendly than any single aisle aircraft.
For the high value customer (Gold, Platinum, Diamond) Delta is a superior product. Sometimes pilots don't quite get that.