Sigh...
The CPU has only once gone for it on 4th and short against me on All-Pro difficulty, except for late in the game when the CPU team is way behind and it's a situation where I would go for it as well.
Some things to consider:
Is your O line made up of 1st and second year players? If so, their aggressiveness and/or consistency rating is garbage, and they tend to get burned more often, regardless of their pass or run blocking ability. Aggressiveness is a huge rating for offensive linemen.
If all-pro rating, where the CPU and you have an even playing field, is too difficult, then Maybe you should tweak the sliders a bit more and/or go back to the previous difficulty level. Or tweak the sliders in your favor and continue to play on All Pro until you are comfortable with it. I can almost feel your frustration, but those sliders are there for more reasons than just making an accurate sim game. They also help balance the play where if you are better in some areas than others, you can tweak them until you find a compatible playing style, regards of the chosen difficulty level.
The note that a guy on your team that you weren't controlling, got hit with a pass intereference when you weren't controlling him... are you suggesting that this isn't fair???
Does the CPU's team that has no guys being controlled by any human, get hit with Pass Interference as well? Is that not fair as well? Quid Pro Quo