sure...just load up the roster from the main menu.....go into roster control and change anything you want for any team.....change the 40 mans, call ups and downs....ratings, add music, whatever
i always do that before i start the franchise myself.....
one thing i dont like that knight does is he changes the pitchers pitch type.....that is fine but i notice he will remove the 4 seam FB and replace it with a 2 seamer or whatever, imo, just about every pitcher throws a 4 seamer, so i dont understand why he removes it when a guy still only has 4 total pitches