The argument is one of "career expectations". The large number of AT guy who've either LEFT AT for SW and other places vs. the number of SW guys that have left for AT and other places illustrates the difference in "career expectations" between SW and AT.
This point, more than any other, proves just how different a career at AT is than SW. If they were equals, why would so many folks leave or attempt to leave AT?
You could argue that more Airtran pilots left because they basically only had one base in Atlanta. If you wanted to live in Atlanta, Airtran was the place to be. If you want to live somewhere other than Atlanta, Southwest was the place to be. It is obvious that since Southwest had more bases you would expect more pilots to be able to find a location in which they were satisfied.
The only fair agreement would be one that puts significant fences in Atlanta to protect the Airtran pilots from the Southwest pilots and significant fences at all non-Airtran bases to protect the Southwest pilots from the Airtran guys.
To protect the Airtran pilots from Southwest simply reducing the Airtran pilot base but maintaining the flying in Atlanta, the fence would have to maintain a proportional protection based on the amount of traffic capacity maintained in Atlanta. In other words, if Southwest decided to reduce the pilot base but maintain the Atlanta flying, the fence protections would have to somehow transfer to other bases so that airtran captains could remain captains and airtran FOs still have upgrade opportunities similar to what they expected prior to the merger.