I feel like the biggest thing you are missing are the playbooks and game plans.
Yea, attributes matter, but do do coaches, gameplans, cohesion, affinities, injury settings, and probably some other factors I'm forgetting.
I can already tell you that none of this matters in multi-player. Most leagues are based on how well an owner can gameplan, assuming competitive rosters.
Getting the right bars on the players so league wide production is correct stops working as soon as game plans are changed from purely AI controlled.
Bars and production are correlated, but not guaranteed. Too many different modifiers for a strong correlation.