Of those discussed:
Pilots: The A's left KC for Oakland. Missouri pols made MLB expand for 69, back to KC and to Seattle. Seattle was not ready, wanted to wait until 72, which was the original plan. Stadium was simply inadequate. Selig bought the team out of bankruptcy to move it to Milwaukee, where baseball had already failed and did not want to be. MLB had to agree because nobody else was there with cash to meet payroll, as if the team missed payroll, every player would have been a free agent in that Reserve Clause era.
Expos: Likewise Montreal was not ready and had to play in a wooden stadium for seven long years, and then had to move into the greatest piece of archetectual malpractice in history. The the owner ran the team into the ground to get it free. And, a foreign enemy could not have done more damage to the Montreal economy on purpose than the PQ types did to it unintentionally.
North Stars: Typical of the NHL. How do you not have a team in the metro area with the most realtionship to hockey in the USA? Idiots.
Senators/Nationals: Actually condidered "Grays", in an attempt to be PC. In any event, newness is wearing off, and we are seeing why the Senators left twice, and why everybody who knew anything understood they they stadium needed to be in Virginia.