As commissioner of a league that often uses stats/categories that are not standard I have been putting the definitions (from MLB's glossary) in the messages of the league to ensure all managers can see and access them throughout the year for reference.

My idea would be to have a tab on the league page with these already done with the stats the league has chosen. It would save room in the message board of the league and be a good way to give more information to the managers, even if it is well known stats.