I wonder why DL would wade into the LAX CHI market.

UA - 12 flights
AA- 9 flights
F9 - 1
WN - 2
VX - 1
NK - 1
Total - 26 flights

DL won't really get any international feed as most people would fly from ORD direct and the Domestic yields have to be miserable with that kind of competition.

AA, UA, and WN all have better feed on the CHI end and the LAX end is a cluster that no one really has any pricing power. DL probably can better utilize their planes/crews that joining the scrum that is LAX / CHI

Plus that doesn't even include the flights from SNA, BUR, ONT.