I think any issues with teams located in the same city or state goes back to the time when the leagues were more independent and in competition with each other to some extent. Would owners today be opposed to, for example, putting the Cubs and White Sox, not only in the same league but in the same division? Is any opposition strictly based on not wanting to switch leagues, meaning the White Sox owner would approve only if the Cubs were moved to the AL and the Cubs owner would only approve if the Sox were moved to the NL? My guess is revenue would be increased by putting teams in the same city/metro area in a single division. Most Cub fans hate the Sox and visa-versa, but since they are not competing during the regular season, I think the fans mostly do not pay much attention to the other team. If they were in competition in a single division, I would think (for example) Cub fans would be more likely to watch Sox games on TV hoping to see them lose. I know that I am far more likely to watch non-Brewer games on TV when one of the teams from the NL Central is playing. If the Twins are on the regional Fox Saturday game, I am much less likely to watch than if the Cardinals are.