The problem as I've stated on this board before is, for the most part you can't "fix" accuracy. QBs tend to have it or they don't. Oh, you can tweak footwork, etc., but no less authority than Bill Walsh says it's the most important thing for a QB to have, and it can't be taught.
I'm pretty sure accuracy can be taught. It's mechanics. The people you say can't be taught either are morons or their mechanics are so bad and can't be improved and they can't deliver the ball accurately. I was a golf teacher when I was young. If you can teach swing mechanics to people...you can teach throwing mechanics. However, there were people who had swing flaws that were a bitch to try and improve...and to be honest...they were always going to have consistency issues.
Now, what may not
be able to be taught, is having the nuts to play QB, and the nuts to sit in the pocket and have a 300lb dude running at you who wants to remove your head...and with all that going on...you then relax, process the information in front of you, and throw an accurate ball with the proper angle & velocity. This may not be able to be taught.
The jury is still out on Petras right now...because he's done it several times...but he's struggling with it, and hasn't been as consistent as he's needed to be.
Brian Ferentz is trying to win games without having to have Petras think too much. If you notice, he's using the naked bootlegs to the sideline where they are easy throws and decisions...quick seam routes where formations have given us a window and Petras doesn't have to look off a LB, or quick lateral throws where Petras is just getting the ball out out quickly to the receiver to get YAC....and then the out throws where Petras can use his arm strength...but they are all safer throws that don't require him to think too much...or do too much.
Listen...Petras played well at Penn State. He had one really bad decision...and if you take away the 4 on purpose throw aways...he's 18-24 with no picks. We will take that all day. Is that not accuracy? He struggled against Nebraska...I believe because that awful pick shook his confidence. He needs to let those mistakes go and just play. The kid has played 6 games against B10 teams...he really could have used a few cupcakes to settle in.