Ummm....that's a pretty meaningless average considering that ALPA merger policy significantly changed over the course of those mergers.

For example, the UAL/CAL merger which was the first significant merger under the current policy which is important considering the major revision to the current policy was to specifically include longevity.

Each merger is arbitrated on it's own merits and considering the three primary components of the current policy I'd suggest that a UAL/JB combination would be quite asymmetric on all three counts and certainly far more than UAL/CAL. YMMV.