CPU varies anywhere between 55-70% in completions......
The QBA being at 70 might appear to be high from the naked eye but remember on Pro Level you very rarely witness the ROBO QB play.
I still see the occasional errant or target throws by the CPU.
The real problem is the Human QBA but that is standard with the game EA makes the Human controlled qb way to accurate...
Anywhere between 0-5 seems to be a comfort zone for the Human player.
I also use 100 Run Block to eliminate a lot of the TFL the game renders on both sides.......you can either reduce Run Block down for Human or either increase the CPU Tackle slider to find a good balance catered to your skill set or team.
I'm averaging roughly 5.2 YPC with Elliot in 9 games but that was inflated do to a couple big runs each game.
It feels natural to me so I won't change or alter the sliders if it doesn't seem unrealistic
Heck Jay Ajayi just had back to back games with 200 yards rushing IRL....how many people would consider that unrealistic in Madden?
So it depends on your skill level and what you think might be acceptable....I no longer play these games looking for perfection because that simply isn't going to happen with Madden