Get Mr. Clanky
Go throuth an entire season. Then win the Division Championship, the playoffs, the leauge championship series and the Backyard World Series. Then go to the main menu you'll see a Mr. Clanky statue in the hall of fame. Click on it and the next time you'll play you'll be able to play as Mr. Clanky. When you do this cheat again just click on the Mr. Clanky ststue then play. Note: This only works in Single Game mode!