What would make a qb with field vision 100 and look off def 92 throw 3 interceptions by game? Lack of protection? Playbook? Coaching?

I would say, lack of protection, good coverage, and bad luck. Everybody has a bad day.

There are a number of factors - and you are accurate in thinking those are effecting the play. The field of vision skill will help the QB identify defending players and also locate an alternate open receiver, so it improves his decision making when he throws the ball. The look off defender skill basically is his ability to move the safety (or other zone coverage db's) out of position by looking at the non-primary receiver, although that competes against the db's zone coverage skill (and does nothing if there are no db's in zone coverage). If the QB is under pressure, his accuracy will suffer. And on the defensive side, if the db's have good man-to-man skills vs. your receiver's route running skills they are going to have good effective tight coverage. And lastly there is just the dumb luck dice roll that could turn the perfect situation into a bad one, and sometimes it does seem that you get all the bad dice rolls in a game.

The coaching is probably the least influential, the coaches are impacting the player development more than they are their game performance.

How does play calling affect this?

You do have a little control in the play calling - the QB will be more accurate and the WR more likely to make the catch if they are more familiar with the play (both the offensive and defensive play for that down), and the defense will perform better if they are more familiar with the play as well. Also, shorter passes have a much better accuracy than long passes, even for QB's with poor accuracy. (The longer the pass, the more important the accuracy rating is.) So if you have a QB with less than optimal accuracy, you can reduce the number of longer passes.

Thanks!

how do you call plays

You don't call plays real-time, instead you put together your game plan, assigning plays by play type and formation based on the situation. Then, when the game is simmed, your coach calls the plays based on the rules you have set.

Here's a blog entry I wrote about how it works:

http://blog.myfootballnow.com/2014/09/the-nuts-and-bolts-of-game-planning.html

Feel free to post if you have any questions after looking at that and we'll all be happy to help!

oh i new that i thought you could call them realtime

Ah, no, we decided to make sure you didn't have to be on your computer during large pre-determined swaths of time to play (even the draft is designed with that in mind) and the most equitable way to call plays with that goal is to build the rules for your coaches to use.