From the wiki
https://wiki.ootpdevelopments.com/in...Totals_Options
Use Pre-Calculated Modifiers
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In a non-replay league with historical players but talent that varies from historical, player output will be closer to what would be expected by their ratings while overall league totals will not be as close. Talent among the high use players varies in such leagues for many reasons. Some are non historical starting lineups, presence of players who retired historically but not in the save, absence of players who were injured in the save but not historically, use of three year or five year rating basis rather than one year, Development set to on, and Talent Change Randomness set to on.
I realized similar information was not provided for auto calc modifiers so I added that (not live yet, approval pending).