Age and longevity.
As much as I respect the effort and thought that went into Rob's analysis, he has utterly and wholly missed the central issue. If one reads the Nicolau decision as well as the counter analysis of the independent pilot, one finds that time and again the US Air pilots came back to the fact that a pilot hired in 1988, who was furloughed at the time of the merger, would end up behind a two year hire at Am West. Two decades of "longevity" were trounced by two years of what? or so the US Air thinking went. No amount of economic reality could help US Air's pilot group come to terms with the "unfairness" of that dichotomy.
The current UAL/CAL situation in no way compares. From the stand point of an independent viewer we are much like DAL/NW except that our "ratios" are not quite as similar. Both MECs need to do their utmost to advocate in favor of their pilot group and if the CAL MEC chooses to grandstand now and again who can blame them since they have fewer pilots and fewer wide bodies.