I have to talk about Yakyu, because something that has never been observed is happening.
Yakyu used to be almost sole sports citizens could watch on TV. The popularity hadn't been dramatically chnaged until around 2000. Since then, the audience rating has been steadily declining. The following chart shows the audience rating on games of one of the most famous teams in Japan.
In order to bring back the fame, Nippon Professional Baseball decided to introduce new systems called "Crimax Series" which allowed top 3 teams in each league to have chance to proceed to Nippon Series. The older system guarantted whoever is in the first place to join Nippon Series. This often resulted in lack of motivation, audience and viewers when a team overwhelms the rest of the teams. Crimax Series at first gave hope to both teams and supporters and it actually increased the popularity.
However, people gradually began to pose questions on the new system saying "140 games regular games are devalued because crimax series is much more important. Teams have only to remain above 4th." In fact, the average audience rating on Crimaz Series has been going down since the system was introduced. (2007 15%→2008 17%→2009 12%→2010 11%)
Also, some Yakyu teams were not in favor of the system because teams at the first place fail to proceed to Nippon series so many times (called tragedy of Hawks).Nippon Professional Baseball also introduced another idea called "Inter-League Games." This also had good effect at the beginning, but the effect has faded away as people got used to the new try.(2005→12.2% 2006→10.27% 2007→9.04% 2008→8.81%)
Both novel tries had temporal effect to bring up the popularity of Yakyu among people, but the effects have faded away after years.
As the proof, TV companies do not broadcast as many games as they used to. In fact, only 4 games out of 7 possible games are going to be broadcasted nationwide for this "Nippon Series" (equivalent of "World Series" in Major League Baseball).
I think the majors Nippon Professional Baseball tried were not idiotic ideas, and were rather reasonable instead. Japanese people simply have lost interest in Yakyu.
I can't come up with any solution to the declining popularity of the Japanese baseball.
It is presumable that people have come to use the internet as an alternative media to TV, which decreased the weight of TV in the society.
I wish I could come up with any good solution.