Interesting. The reports that I saw in the past were from the State of Hawaii Tourist Bureau and I think I recall the annual numbers; if I remember correctly they were local traffic that didn't include connecting pax. What we see here are stats for a single month which is going to be biased toward or away from seasonality. SAN's Hawaii season is the summer which is pretty much the opposite of a lot of places which see most of their HI business in the winter.
In any case, this certainly gives an idea of how things stack up as far as mainland markets to Hawaii. (I'll try to find what I used to look at.)
I have no doubt that the report you read was true at the time.
Remember I was dumping April 2019 data, and Southwest began flights from OAK to Hawaii on March 18, 2019.
In December 2017 United increased their service from Denver to Hawaii. San Diego does not have the connecting pax to compete with this increase.
Kona: Seasonal service will increase to daily, year-round service starting Dec. 20
Lihue: Seasonal service will increase to daily, year-round service starting Dec. 20
Kahului (Maui): Seasonal service will increase to daily, year-round service starting Dec. 20
Honolulu: Daily year-round service will continue unchanged
Also in 2017 Hawaiian began A321neo flights from PDX to Maui to compete with Alaska airlines.
I will continue to say that I think 9 daily flights to the Islands (in the summer especially, with no wide-bodies) will not be too many. (And again, I'm pretty sure WN will be using a fair number of their seats for connecting pax coming in from points beyond.)
Repeating table Flights origin pax & seats (April 2019) destination anywhere in state of Hawaii
1127 LAX 174,525 212,442
554 SFO 99,703 123,251
457 SEA 76,056 85,351
325 OAK 45,246 52,026
215 PDX 32,591 38,853
120 DEN 26,005 31,871
151 SAN 25,423 28,332
It is certainly possible that SAN will surge ahead of PDX and DEN by next year. I think if it passes OAK will depend if you are counting origin and destination passengers or including transfers.
Southwest has slightly more physical room at the Oakland terminal right now to comfortably do transfers.
Oakland 124 daily departures from 15 gates on Southwest
San Diego 122 daily departures from 11 gates on Southwest
Los Angeles 125 daily departures from 12 gates on Southwest
The lack amenities in Terminal #1 at SAN coupled with how incredibly busy the gates are means that I have heard passengers swear that they will never transfer again at SAN on Southwest. In general 70% of Southwest passengers only fly one segment.