Modern Oldies – Rules

Modern Oldies Baseball is built around a simple premise: what would baseball have been like in the 1930s with divisional play, integrated rosters and modern financial rules?

First, a few of the basics:

  • GENERAL: The league is based on a modern financial model (scaled to the appropriate year). So you would have free agency in the 1930s but the financial base in prices/salaries/etc would be scaled to the era of the Great Depression.
  • STARTING FORMAT: The league will begin in an alternate 1931 where MLB expands to 20 teams, allows the signing of Negro League players and all teams are affiliated with one minor league club at the AAA, AA, A, B and C levels. Both the National and American Leagues are split into two five-team divisions and the division winners will face each other in a best-of-seven League Championship Series to determine the World Series participants.
  • ON-FIELD FORMAT: The on-field atmosphere of the season being played in terms of play style, roster management and rules will be used. So for 1931, four-man rotations, an elevated hitting environment coming off the historical 1930 season, no designated hitter in either league, etc will all be in effect.
  • GM PARTICIPATION: The commissioner would prefer not to be the “participation police” but reasonable expectations will need to be met. These are simply to submit exports on a fairly regular basis, paying attention to Slack and the forum, and replying to other GMs in trade discussions. The commissioner may replace any GM who becomes absentee or fails to treat others fairly.
  • GM FIRING: Firing in the game is on. If a GM is fired he can take one of the Northern League teams until such time as another GM gets fired and he can rejoin the majors OR another GM may elect to switch teams in which case the fired GM may be hired to take over the vacated team.
  • SIM SCHEDULE: Games are simmed Monday thru Friday, with exports due by 7am Eastern time.
  • SIM PERIOD: Each sim period covers one week during spring training and the regular season. Postseason sims will be split to cover games 1 & 2, 3 & 4, 5 & 6 and then game 7 (if necessary). Offseason sims will vary in length and the commissioner will provide a schedule on the league’s Slack channel for reference during the October to February offseason.
  • COLLECTIVE BARGAINING: There will be no work stoppages in MOB. The model we will follow is essentially the CBA as it existed in the 1990s.
  • FINANCES: At league start all teams will have identical incomes and non-player expenses to level the playing field as much as possible.
  • TRADING: Trades are typically run at the end of a sim period. The only exception to this is the trade deadline sim.

And more in-depth on the specifics:


To balance the desire for a modern style financial model with the need for a manageable (and historically plausible) system, MOB will use the built-in pre-2012 CBA compensation mechanics built into OOTP. The way this operates is described below from the OOTP manual:

In OOTP, when a team loses a player to free agency and that player is signed by another team, the original team potentially receive two types of additional draft picks in the upcoming first-year player draft as compensation for that signed the free agent. These picks are ‘compensatory’ picks – from the team that signed the free agent – and ‘sandwich’ picks – added onto the end of the draft round, as they usually are in real life. For a Type A free agent the team losing the free agent gets the other team’s first round pick as well as a sandwich pick after the first round. (With the exception that if the first round pick is in the top half of the draft, they get a second round pick instead). For a type B free agent the team losing the free agent gets a sandwich pick after the second round only. There is a formula similar to the Elias one (but not exactly the same) that computes who the top free agents at each position are in order to rank the Type A or B classifications. A team will receive no compensation for a player classified as “No Compensation”.


All players entering the league for the first time will be eligible for the MLB Amateur Draft in the season in which they began their pro careers.

  • Draft order is based on the previous season’s results with the picks alternating by league and the league’s alternating the first overall pick.
  • The AL team with the worst record will pick first in odd-numbered years and the NL team with the worst record picks first in even-numbered years.
  • The in-game draft will occur in early January.
  • The draft itself will be done outside the game, utilizing StatsLab. The draft will begin one day after the commissioner releases the draft pool (it usually works out to be toward midweek and runs through the weekend). Pick times are slotted with shorter intervals in the later rounds. Any portion not finished “live” will be run by the game on the in-game draft day.
  • Drafted players must be signed. If you do not sign your player he goes back into the draft pool the next season. As was the case prior to the 21st century and in accordance with “perfect foresight” in terms of people knowing when specific players enter the draft (and therefore purposely not signing a 1st round pick to get a comp 1st rounder the following season), teams do NOT receive a compensatory pick for not signing their draftees. So try to make sure you sign them.


All 20 teams will have five minor league affiliated. These clubs will be aligned – in general – with the actual minor leagues and their clubs for the specific season being played and in many cases, historical affiliations will be honored. This will not be possible in all cases as some clubs (the Cardinals in particular) had many affiliates while others had few (or sometimes none).

The “short season” and rookie level leagues will follow the old style classification system as B and C level leagues respectively. All minor leagues will begin play in April and play approximately 140 game seasons.