It seems to be random.
My friend and I use the All Madden set in an online franchise, only difference is we lowered block in the back to 50.
I had a game where there were a couple bitb penalties called on both teams. He had a similar game.
Then I had one game where I got called for 10 bitb (basically every running play late 2nd quarter through the third quarter) and the cpu had 5. I would have had more, had I not completely abandoned the running game...