The methodology they use also rewards consistent disloyalty.
Exactly. Pirates fans not attending in the early 90's helps them in this list.
Also
"The Montreal Expos, Washington Nationals, Arizona Diamondbacks, Florida Marlins, Colorado Rockies and Tampa Bay Rays were not considered due to a shortage of data and the statistical anomalies stemming from those being either new franchises, relocated franchises or a team that folded."
Do you think Forbes knows that the Expos and the Nationals are the same franchise, or that while one franchise has relocated, no franchise has "folded"?
Move along here.