First off, glad you are enjoying these....sounds like you built a powerhouse squad.
As to your comments, you're right about penalties...I mean, yes, we
could get more penalties, but the ones we could add to the mix (offsides, holding) would require tweaks to those sliders that would totally exacerbate the sack issue.
The injury slider is tough....and is a matter of taste. When you bump it up, you get more injuries....but it seems like QBs REALLY get hurt a lot...especially on the other side when they are taking sacks. I personally don't love the idea of facing every team's second or third stringers every game. Feel free to bump it up if you'd like...just be aware of the potential consequences.