OOTP Baseball:Customizing OOTP/Customizable Data Folder
OOTP's moddable files are located in the customizable data folder.
The default installation path for this folder is:
Steam Version: [DRIVE]:/Program Files (x86)/Steam/steamapps/common/Out of the Park Baseball 25/data
Standalone Version (Fastspring): [DRIVE]:/Program Files (x86)//Out of the Park Baseball 25/data
Mac ????
The folder can easily be found in the Troubleshooting tab of the Game Settings Menu.