In season mode, the CPU will accept all
your trades (at least in rookie mode). You can trade players that you do
not use a lot for other players on other teams that are very good. For
example it is possible to trade Marcus Thames to the Diamondbacks for
Randy Johnson.
More broken bats:
At the main menu, go to "Rosters" to
create a player. Enter the player's name as Keegn Patersn, Jacob Patersn,
or Ziggy Patersn, then draft one of them as a free agent.