This could be closer to reality than one might think. From 1999-2001 UAL hired about 2000 pilots the mainline. Around the same time CAL also hired 2000, except they weren't to the mainline, they were at XJT, which was then spun off without any resistance from many pilots who don't want "those" kind of pilots on the property. This may be coming back to haunt them. There is a huge whole in the CAL seniority list at that point. I don't see it so far fetched to have an "adjustment" of sorts for this, advantageous to the junior UAL pilots, not so much for the CAL pilots.
You have no clue!