I'll let WN's Jan traffic report speak for itself.
http://www.swamedia.com/releases/southwest-airlines-reports-january-traffic-2
Trips flown (7.4)% year over year 2013 vs 2012.
The numbers will repeat itself over and over again this year.
WN's capacity (ASMs) were down 2.6% but LF was pushed up by 3.6 points.
Still, WN's LF is one of the lowest in the US industry.
and yes, I get the whole idea of getting rid of the connecting traffic and carrying them on nonstop flights.
but that only works if you have a superior schedule to your competitors - which is not necessarily the case in ATL (Atlanta) and why the likelihood of WN gaining average fare parity with DL is slim. With costs only a few percent behind DL, WN can't remain in the market with a double digit plus revenue disadvantage. The reason why WN can operate 4-6 flights/day in other markets where there is no network carrier is because WN can get by with it. But it doesn't work in hubs like PHL or ATL where the legacy carrier has 2-3X more flights than WN and becomes the carrier of choice in the market because of frequency.
DOT data shows that even in the local ATL market, WN is losing passengers to DL and DL is enjoying larger average fare gains than WN.
and your argument of pulling the connecting traffic out of an airport is precisely one of the arguments AGAINST WN gaining more gates at DAL.
Even in the peak summer season of 2013, WN carried 35% connecting traffic thru DAL. They also used an average aircraft size equivalent to the 737-700.
When one-third of the passengers are "just passing thru" and WN is using the smaller of the two aircraft in its fleet, it is hard to argue with a straight face that WN should gain two more gates when the equivalent of 5 are tied up carrying connecting passengers and WN schedules few if any 738s at DAL.
Further, WN's LF at DAL at 74% is well below its system average which means it could push up the LF to levels comparable to its system and sell thousands of more seats per day.
It also takes the wind out of the argument that DL's use of large RJs and 717s takes up valuable space when DL boards 100% local traffic (no connections).
But, for now, WN is absolutely reducing the number of flights it offers even now - and the DCA slot awards haven't begun, let alone the new DAL flights.
WN will have no choice but to reduce service on its core network in order to provide aircraft for its new opportunities. That is happening already with very few 717s delivered and most of the new opportunities still down the road in 2014.