We are somewhat casual in the sense that we don't put many hours in Madden these days, but we are fans of true simulation. Yards per play is the way to go and the way you build sliders should be the base for slider development. I truly appreciate the work you've done.
Have you thought about running your passing numbers as:
AY/A - adjusted yards per passing attempt: (pass yards + 20*(pass TD) - 45*(interceptions thrown))/(passing attempts),
Or
NY/A - net yards per passing attempt: (pass yards - sack yards)/(passing attempts + sacks)?
It would help you analyze the risk/reward balance of passing when compared to NFL. Like you said, Madden gamers are more aggressive.