[Steve Kuffrey]

Because of the sheer volume of data that the game currently saves:

Major league career stats
Stats for each season(more detailed than career)
Minor league stats season
Minor League stats career(20 seasons I think)
Post-season stats season
Post-season stats career(not certain of the length, 15 you say-not doubting just don't remember)

This is just for players, lots of team data stored as well as player records, highs for career, etc

For every player in every league these are possible, so I'm sorry about the lack of detail in my first response. I hope this clears it up.