Play with Matt10's sliders. You'll see a very nice (and realistic) variety of games regarding passing stats.
Here are some things to consider when playing on Heisman:
1. The CPU will know when you're blitzing and will often, though not always, slide protection or move a back or a TE over to help out. This happens most with QBs who have high awareness. So be prepared to audible out of a blitz call if you see the QB adjusting to it so as not to get burned.
2. Adjustments have a HUGE impact on your pass defense! If you call for aggressive ball stripping and pass defense, you will get lots more attempts by defenders to knock the ball out of the receivers hands upon contact and lots more attempts to cut in front of the receiver to get the ball. Be very careful with conservative and aggressive zone defense though. Going conservative backs way off shallow routes and will give up completions in exchange for tackles. Going aggressive will murder dumpoffs and quick hitters over the middle but will get you killed deep.
I find that when I'm struggling to stop an attack, the best thing is to try to change my approach using some of the strategy tools in conjunction with playcalls.