Blah blah blah ... the reality is that Delta at NRT is shrinking - has been for years, and continues to as the 747s get parked.
Routes have been cut - not just to Asia (ICN, PEK, PUS, KHH, HKG), but also to the U.S. (SFO). And the routes remaining have, in many cases, seen capacity reductions from where they were 10 or even 5 years ago (747s now 777s or A330s, etc.).
All the focus on comparing Delta capacity in any particular place to United/ANA, or AA/JAL, misses that, regardless of capacity, those JVs are able to offer pretty much comparable U.S.-Japan schedule presence (the same if not in some cases more frequency) to Delta, even if in some cases on smaller aircraft. And in Asia-Japan, those JVs obviously handily dominate Delta in schedule presence.