This is interesting, help in editing is always welcome. I am working time to time on the roster file for MLB14 The Show for PSVita.
I already found where to look in a roster file game save to hex-edit the following data:
Weigth, Height, SerY -years of MLB Service-, SerD -days of MLB Service-, Team, Position, 2nd position, Born in USA -yes or no-, Jersey Number, Age, Switch batter -yes or no-, Throwing hand and Skin color.
In order to identify the location of player's ratings we only have hex-editing there is no other way at this moment. I found the above that way.
I also know how to edit the schedule editing game files and perhaps from a game save too.