What WarEagle said is how I understand it too.
Here's what I understand:
1) The primary receiver is chosen presnap.
1.a) The primary receiver is chosen at random.
1.b) The route of a receiver that matches the play call gets heaviest weight.
1.c) Some receiver running the route that matches the play call is designated 1st in the priority. That player is weighted heavier than all others.
DICE ROLL
After the snap:
1) The QB stares down whoever was randomly selected in the dice roll.
1.a) The selected receiver finishes his designed route.
2) After waiting for the selected receiver to finish his route, the QB decides whether he's going to throw it there.
2.a) The QB's FOV influences if he even sees the receiver finish the route, sees other receivers in the area, gets distracted by a cheerleader, and balances his checkbook.
2.b) The QB's Arm dictates if he'll even throw it to that spot if he sees it in subbullet b.
2.c) The QB finishes making the decision.
3) Passing release dictates how long it takes from 2.c to the actual throw.
3.b) Arm dictates how quickly the ball arrives at the spot.
4) The accuracy formula dictates how close to the actual spot the ball arrives.
I mean, if I understand it all correctly that's how it goes. I'm definitely sure about the balancing the checkbook point. That's essential.