re: O'Neal
It could be a whole lot of different things including:
- Dumb luck. There is a significant degree of luck involved in each simulation.
- You may have low offensive flow, particularly from your PG. He may have only gotten the ball in situations where he was getting non-optimal shots
- Opponent's defense. You might have had him lined up against a much better defender, and the opposing team as a whole could be a very good defensive team.
It's hard to tell but it's likely that it's some combination of all three things.
re: Ratings
Ratings don't just reflect the stats that show up in the box score. It also reflects things like helping the offensive flow and playing defense. If your starting SG isn't dishing out a single assist then I would expect him to get a low rating.