Choosing a number is not just arbitrary. One must consider the mathematical mechanics of a schedule proposal. First, consider the regular season. Ideally it should be set up so that every team has the same schedule, which means the same number of games against each team within the division, the same number of games against each team in the other two divisions in the same league, and the same number of games against each team in the other league, with an equal number of home and away games against each opponent. That requires an even number of games against each team. How could this work? Regarding interleague play, the current arrangement of playing each team in one of the three divisions in the other league, rotating each year, is probably the best that can be hoped for. I think the so-called rivalry series should be eliminated. The novelty of the Cubs playing the White Sox, the Yankees playing the Mets, etc., has worn off, IMHO. The probable best option is to have 20 interleague games, two home and two away against each team. Next, regarding intraleague extradivisional opponents, let's set 8 games per team. Since there are 10 such teams that's 80 games. That brings the total of games so far to 100. Then, regarding intradivision games, 14 games per opponent is 56 games. This makes 156 games, which to me sounds about right. Regarding the postseason, I think advancing 5 teams from each league is the best option and I like the current format. Many will say that a 1-game elimination series for the two wild card teams makes it more unlikely that the better team will advance, and that point is well taken. However, the strong reason in favor of the current format is that it gives a team more incentive to win its division. That said, I wouldn't oppose making the wild card series a best-of-three if the regular season is reduced to 156 games.