I'd like to see a seniority distribution for Delta. I suspect that they shaved the top off the "years at Delta" category by offering early retirement in 2004 and earlier this year. A senior pilot who didn't take early out and access their lump sum distribution (instead of the pension) was rather stupid.
I would think you have generational extremes - less than 5 year tenured pilots are not vested in the pension - so they might be willing to go for broke. Some intermediate tenure pilots might be willing to strike, those with say 20 years don't want to blow the whole thing away.