The only rivalries that exist now are the regional ones within a division. When the divisions were expanded, there were as many as seven teams in a division, which created more rivalries. And now the unbalanced schedule makes it where outside of your own division, you only see the rest of the teams in the league six or seven times a season.
I remember when east coast teams made the second trip to the west coast against the same teams, and vise versa. Unfortunately I never got to see the single division leagues that existed before 1969. Having just 10 teams in each league must of created some of the best rivalries baseball has ever seen. Rivalries that do not exist now. Outside from division foes, it has become a sight seeing trip when a team makes their annual road trip to a team that is in the same league and a different division. The same amount of trips make to a particular interleague team.
Of course, this was intended to make the divisional games mean more and to keep teams with losing records out of the postseason (like the Texas Rangers would have been in 1994 hadn't it been for the strike). So, it serves its purpose. Next year, it will be set up where each team has exactly four teams to hate. The other 90 games will be a trip to the country club, where they are simply playing a game.
We can remember back to the season of 1986, when the Mets, on their way to the World Series, were involved in four separate bench clearing brawls with four different teams. The only team they fought with that was in division was the Pittsburgh Pirates. All three of the other teams, the Reds, Dodgers and Braves were all in the NL West. More games versus each team made each games mean more and created more tension between the teams.
Its fair to be in favor of balance. It makes sense to have the same amount of teams in each division and in each league. And the unbalanced schedule keeps teams with losing records from reaching the postseason, for the most part. Perhaps the 18 games against each divisional opponent could be reduced by a little bit. Maybe some of the interleague games could be reduced, especially the six interleague games played each year against the same team. That could open up two or three series a year. That would be two or three more series that could be played against teams from the same league and other divisions. I personally think that would work out better.
1968 was the last season where there were single divisions in each league. The NL consisted of the pennant winning St Louis Cardinals, Giants, Cubs, Dodgers, Reds, Braves, Pirates, Phillies, Mets and Astros. The AL had the evenutal World Series Champion Detroit Tigers, followed by the Orioles, Indians, Red Sox, Yankees, Athletics, Twins, Angels, White Sox and Senators. The addition of teams like the Kansas City Royals and Seattle Pilots (later became the Milwaukee Brewers) in the AL and the Montreal Expos and San Diego Padres in the NL forced the leagues to go to two divisions, which lasted all the way until 1994. The AL East consisted of the Yankees, Red Sox, Tigers, Brewers, Orioles and Indians, with the Toronto Blue Jays joining in 1977. The Al West had the Athletics, Angels, White Sox, Royals, Senators (who became the Rangers in 1972) and Twins, with the Seattle Mariners joining in 1977. The NL East had the Phillies, Mets, Cubs, Cardinals, Pirates and Expos, with the Florida Marlins joining for the 1993 season. The West had the Giants, Dodgers, Padres, Astros, Reds and Braves with the Colorado Rockies also playing in 1993.
The three divisions are very close to the way they are now, with a couple of exceptions. The Tigers remained in the AL East until 1998, while the Brewers were in the AL Central. When the Brewers moved to the National League, the Tigers moved into the AL Central and the Tampa Bay Devil Rays took their spot in the AL East.
Though I like interleague play, I would rather it be reduced from what it is now. I am looking forward to my first ever trip to the Rogers Centre in Toronto to see the Mets play on May 18th and 19th. It is nice to catch a team play an opponent it seldomly plays. But do the Yankees have to play the Mets six times a year? I think its overkill. And what does that do to the balance of power in the NL East when a division rival plays six games against a much lesser team? Kind of takes a step back when we talking about each team playing an unbalanced schedule of the same teams in their division 18 times. I'd rather the Mets renew their rivalry with the Cardinals like they did in the 1980s, or even the Cubs or the Reds like in 1969 and 1973. Right now, there is no reason for those teams to dislike the Mets and vise versa. The same can be said for all teams in all division. I doubt there will be any tension when the Tampa Bay Rays make their yearly trip to Seattle. The same for when the Diamondbacks make their one spot in Miami. I say, back off a couple of division and interleague games and bring back some of the old school rivalries.