It's a grab bag of reasons.
Your defense is weak. SS/CF need upgrades. 85 across the board at SS, 85/75 range/glove in CF. There are exceptions where the bat just outweighs the lower D. Yours do not.
You don't have a single impact bat and most are back-up level hitters without the D to make them back-up players.
To me, it looks like you have three legit BL pitchers(although I'd use Turk White while most wouldn't).
Use 70 splits as your baseline for both hitters and pitcher. 55, 63, 65, etc are going to produce mediocre results.