There's a published methodology on how the S&P 500 works. It's quite predictable, as this is a desirable feature on any index. While it's true that there's a human index committee that meets, it's mostly for tie breakers. They strive for diversity and typically lean on precedence to make their picks.

Also, almost nobody thinks the S&P5 is worse than the Dow. I'm not sure how you can back that up.