You can sim games using any roster from any year. Pretty fun to play around with. I had the 98 Yankees edge out the 27 Yankees 4 games to 3 (coming from behind 3-1) and the 56 Yankees beating the 56 Dodgers (again) 4 games to 2. Ironically, in that last one, Don Larsen pitched two complete game shutouts, one of them a two hitter.
Unfortunately you can't sim whole series, so you have to go game by game. You can switch home and away though, which is good, although I don't know how much effect it has on the game.