I just registered today, because for the first time ever (after a year plus of reading these boards!) I think I've got something constructive to say!
In Football Manager, we have what are known as (the infamous) Grey Players. They are players, with real names, and real, visible ability ratings, who fill in when teams have fixtures but not enough real players to fill out the team - usually youth or reserve team games.
They can't be signed by other teams, and in FM can only be used in the first team if there aren't enough real players - so I was thinking maybe the same thing could happen in OOTP? If, in a historical game there are minor leagues running, but not enough real historical players then maybe the game could have some Grey players fill in. That way you have full teams, and therefore real, meaningful stats, and the fake players won't be able to be called up to the Major league teams.
Just my