I assume you're referring to Historical Exhibition mode.
For some reason, Julio Franco is not included on the 2003 Braves roster. I see no reason why he didn't get listed on the Opening Day or End of Season rosters for 2003. He's listed on a roster every other season that he played in real life. But not 2003. Even when I add him to the OD and EOS roster files for 2003, he still does not show up in the game when I use Historical Exhibition mode and choose the 2003 Braves. However, he does show up for the Braves if I create a regular 2003 historical league.
I. Am. Stumped.
ETA: I used Historical Exhibition mode and chose the 2004 Braves. This time, Franco is there. So, why not 2003? I have no idea.