This game, as of all baseball games, are very easy to cheat on. In order to get better results in all of your baseball games, just go to Team Management in your options for Dynasty or Owner mode, then go to Rosters, and then Create-Edit Player, and then pick any player at all you want to edit. You can make your entire team with all perfect stats and be undefeated for the season. Or you can simulate all your games and still have an incredible record. My highest simmed record so far is 140-22. Have fun!
In Owner Mode, purchase all the available Ballpark Upgrades (Make sure each upgrade has reached its maximum level). After purchasing your final upgrade, an extra option will appear in the Buy Assets menu. This new Option will be called Secret Stuff.
Create a player called "Katie Roy" (Capitalization matters!) and you will have unlocked all rewards.