The standard active roster in baseball is, and has been for most of my fandom, 25. But for this tournament, I'm setting the rosters at 24. The figure works for all three seasons:
1969: While I don't have the new set yet -- it's not even available for order yet -- the original basic-play-only set was largely limited to 24 players per team. There was a basic 20-man roster (eight pitchers, two catchers, and either six infielders and four outfielders or five infielders and five outfielders), plus a handful of additional players. A few teams had five additional players, but most had four.
And, frankly, with roster changes far less frequent in 1969 than in today's game, 24 works. The Twins for example. The "missing" player is Tom Tischinski, third-string catcher who played in 37 games and hit .191. We're not exactly missing a key piece of the puzzle by missing him.
1987: Collusion was at its height in 1987, and while the main piece of that story was the refusal of teams to sign free agents, another piece was the under-the-table agreement to cut a roster spot. Teams carried 24 players that year, not 25. Even more, perhaps, than in 1969, 24 players works.
2009: Everybody carried 12 or even 13 pitchers. This is a dubious use of roster space even in the long regular season, and even more so in the context of a sequence of seven-game elimination series. Deleting a roster space can be viewed as simply deleting the fifth starter, few of whom would start in a best-of-seven anyway. Here 24 works because 25 is a waste.
Injuries. Yes, I will have them.
In both the defunct Free Press league and my solitaire Presidential League, injuries were strictly remainder of game. Here I'm going to roll the 20-sider and allow multiple-game injuries. I will have a five-game disabled list available, and it will allow a use for the extra players included in the 1987 and 2009 sets. I hope there will be some extras in the 1969 set, but that's unknown.