Sounds for Your Homerun:
While running around the bases hit S, W or A (air horns), D (whistle)

Large Players Mode:
Simply hit a homerun with a player over 250 lbs. This is usually Babe Ruth or a Hefty Created Player.

Babe Ruth:
message: To unlock Babe Ruth and make him available in the Free Agent Pool. You must hit a home run with the PITCHER. It can be a created pitcher too....so just create one that has the ability to hit homeruns.

Island Stadium:
To reveal a secret stadium called "Island Stadium" usable in Exhibition Mode simply score 3 or more runs at the Giants New PAC BELL PARK.

Cy Young:
To release Cy Young and make him available for the Free Agent Market.

You must throw 5 innings or more of shutout ball (can't let the other team score basically) or WIN 25+ games with the SAME pitcher in Season Mode.

Satchel Paige:
To get Satchel Paige in the free agent pool,strike out 5 batters in a row with the same pitcher in the same game.

Mickey Mantle:
All you have to do to get Mickey Mantle in season mode is hit a grand slam with anyone and after the game the Mick will be in the free agent pool, and he maybe the best player on the whole game.

Jackie Robinson:
Steal 5 bases in a single game and you will unlock Jackie.

Flaming Ball:
Strike out 9 batters in a game and you will get the Flaming Ball reward.

Get StrongArm:
Turn a TriplePlay

Get Power Up Speed:
Steal 6 or more times in one game