Version 12a Patch

Version 12a Patch Information

This page describes the enhancements and bug fixes that are included in the version 12a patch. Keep in mind that a patch is not a complete copy of the game; it includes only the changes that have been made since version 12 was first released.

Because the version 12 game and the version 12 encyclopedia are downloaded as separate Windows programs, we have provided patch files for each of those programs. If you use the Encyclopedia, you'll need to download and install both of them in order to get all of the changes.

Please read this page to learn more about the changes in the version 12a patch, how to know whether you already have version 12a installed, and how to download and install the version 12a patch to update your already installed copies of the version 12 game and encyclopedia.

The "Starting Pitcher as DH" rule and the 2022 Season 

Beginning in 2022, MLB introduced a new Starting Pitcher as Designated Hitter rule -- commonly known as the "Ohtani rule". This rule allows a team to choose the same player as both the starting pitcher and designated hitter (DH) and then make in-game substitutions as if there are two different players in the lineup.

If you have the version 12a patch installed, this new rule can be set with the "Starting pitcher as DH" option in your League or Organization's Rules/options page and will be enabled by default for the 2022 season.

Therefore, it will be necessary to have the version 12a patch installed to be able to play the 2022 season and take advantage of this new rule.

Enhancements in the version 12a patch

  • Added support for allowing a player to both pitch and DH in a game (the "Ohtani rule"). Includes updates to the computer manager to allow player to remain in game as DH if removed as pitcher and vice versa.
  • Updated Historical Ballpark database to include all parks through 2022. 
  • Updated Historical Player database to include all players through 2022.
  • Updated Historical Era database to include all eras through 2022.
  • Increase maximum limit for Playing Time Penalties to 500% (current limit is 250%)
  • Improved substitution logic when saved lineup includes a player without a position.
  • When migrating a database league Era IDs will be carried forward to the New season database, if possible, instead of assigning the Neutral Era.
  • Add check for in-progress games when converting a database with option to delete saved games and continue or reject the conversion.
  • Added three new transaction type pairs: 7 Day IL/Activate, Shutdown/Return, Paternity/Return.
  • Improved Computer manager logic for pinch-hitting for platoon partner when protecting a late lead.
  • Update fielding reports to display baseball notation for part innings (i.e. .1 and .2 instead of .3 and .7)
  • Added additional schedule templates for schedule formats that were originally excluded from version 12.

Bug Fixes in the version 12a patch

  • Various fixes for adding new column headings in customized and memorized reports.
  • When working with depth charts, Move and Exchange menu commands now include additional utility player slots.
  • When the bullpen warmup rule is enabled, replacing an injured player with a pitcher that has not been warming will not generate a warning message.
  • Corrected issue in Saved lineups that caused unsaved lineups to be erased when a new lineup/depth chart is computer generated.
  • Fixed standings report to correctly show extra-inning records for scheduled games of all lengths.
  • Corrected issue with the Update streaks & usage command that would result in a crash when there are no remaining unplayed scheduled games.
  • Tidied up field names and column headings in Batting profiles and Pitching profiles reports.
  • No longer possible to inadvertently insert a pinch hitter from the player bench menu after a game has been completed.
  • Corrected postseason bracket display for teams with a bye in the previous round. 
  • Fixed error when deleting the last season in an encyclopedia (ENC).
  • Fixed bug that caused tiebreaker "Playoff" games to be excluded from the season standings and displayed in the schedule incorrectly (ENC).
  • Fix for bug that caused boxscore files to be saved to an incorrect location when generating a website (ENC).
  • Fixed HTML table formatting for season leaders and career Leaders reports (ENC).

Keeping track of versions

If we release more than one patch, we will identify each patch with a different letter: a, b, c and so on. We will also create a new master file that will be available for any new downloads of  version 12 games and upgrades. In other words, if you purchased DMB12 after the latest patch was released, chances are you do not need to download and install any patches; those corrections will already be included in the version that you downloaded from the Diamond Mind website.

To find out whether your copy of DMB12 has already been updated, start the game and from the Help menu, click About Diamond Mind Baseball. If the window that pops up reads "version 12a", you know you already have the corrections that have been made to date.

DMB Leagues

To ensure full compatibility with the addition of the new "Starting Pitcher as DH rule" it will be necessary for all league members to be using version 12a if your league will be based on the 2022 season database. 

Even if your league is not planning on using the 2022 season we strongly recommend that everyone upgrade to version 12a so the game's behavior is the same for all managers in the league.


For leagues that use NetPlay to play some or all of their league games, it will be necessary for all league members to be using the same version to be able to connect. In other words, all members should upgrade to version 12a to ensure NetPlay compatibility. It will not be possible to establish a NetPlay connection between a computer with version 12 and another computer with version 12a.

Downloading the patch

To download the patch installation file, click the link provided below to open the download page on the Diamond Mind website.  From the download webpage, click the "Download Now" button to start your download.

Depending on your browser settings, the browser should either start the download immediately or ask where you would like to save the file. If prompted, choose where to save your file on your computer. The usual location for files saved from the Internet is the Downloads folder in your Windows profile.

If you encounter a warning from your web browser when you download the patch installation file and the download does not complete, please see the following topic on the Diamond Mind message board for the solution.

xxx.exe was blocked because it could harm your device

Installing the patch

Once the patch installation program has been downloaded to your computer, you can install it by finding the file named dmb12a_patch.exe (may appear as dmb12a_patch) using Windows Explorer (or some other tool for browsing your hard drive) and double-clicking on that file to begin the installation process.

Before you install the patch, complete any games currently in progress and make sure that DMB is completely shut down.

When you start the installation process, you will be asked where you would like to install the updates. The installation program suggests C:\dmb12 (or C:\dmbenc12 for the encyclopedia), which matches the suggested location in the original installation program. If you changed this location when you installed DMB initially, you must specify the same location when you install the patch.

Installing the patch will not affect any of your settings or any of your player ratings, statistics or other data that is stored in a DMB database. After installing the patch, you can continue to use DMB12 and your databases without interruption of any kind.

Download Links

Download the DMB 12a patch (5.71 MB)

Download the DMB Encyclopedia 12a patch (1.12 MB)