It's very simple: They don't have enough airplanes to do their schedule. And crew shortages. Plus their scheduling/dispatch organization makes a Part 135 outfit flying Beech 18s look like a model of efficiency.
The old ALPA PAN AM group is no more. When Fink shutdown Pan Am last Oct, that was the end. Boston Maine Airways now flies 727s with the Pan Am logo on them. Different planes, but the same logo. As of now, I don't think their FSDO has approved the former Pan Am planes on their certificate.
Maybe other Pan Am pilots can chime in on the ALPA part. I know that Fink let very few if any Pan Am pilots come on board the Boston Maine train (wreck).