The only game I've ever felt was scripted was MLB: The Show (with Pedroia on the cover). It seemed like no matter how I threw a pitch, with or without the pitching meter, whether the pitch was "perfect" or off the mark, the ball was going to hit with SOLID contact by the computer when I finally got 2 outs. I dont think the football games are scripted but I do believe in the averages some1 mentioned earlier. If you're working with a QB with an accuracy rating of 83 and manage to complete 3 or 4 straight passes, eventually, you're gonna overthrow and miss some open recievers.
To me, the issue is when you KNOW you've got a good QB or a good reciever and balls thrown right on the numbers are miraculously dropped or a CPU linebacker does some Russian ballet spin to get 7 feet in the air and snatches the ball. But it's also a video game with scripted animations and the game somehow has to make those actions link up.