stick with default and change 1 or a few unrelated things at a time.
lots of misinformation in forums. be wary. group think does not equate to "fact"
don't worry about the peanut gallery.. worry about what you like. if you want it similar to mlb, go read about how 'that' works in the mlb from reputable sources and not opinions in forums (including mine when you find them).
i have normal aging and i see guys in 40's in a similar proportion.. yet in forms i see some calling for extremely slow aging values.. .i can only imagine the effect. it's not that it's realistic, it because it matches their perception of how long careers hsould be.
and it's wrong when compared to reality, objectiveley speaking, but not "wrong" to use in a video game.
imo, most things i dink aroudn with i do shift it toward what i want to see, but it almost certainly comes with a repercussion somewhere else that is worse or unfixable
not to say i do not deviate from default here and there... but rarely to a large degree. recent expiriment: low accuracy, low TCR... actually like it but may yet find something screwed up due to that change. i have suggested things in past that i have reverted from doing shortly afteward... i hesitate on givng specifics, since i know it's a possible result.