Hi, I'm a former NWA flight attendant. The window shade thing is just some flight attendants being overly cautious. The only ones that HAVE To be in the up position are in the very first and last row. This is to provide another point of reference in an evacuation. As you stated there was no FAR on the window shades. But many times, there are company rules that are in the flight attendant manual. As for the seat back you are correct, as long as it not blocking someone from exiting it's fine. But try explaning that to some pax's. So it usually just better to have uniformity. Back to the original post of the soccer ball, that's crazy. I've never heard or seen anything like that. I have seen air casts explode in flight. But that's about it. I just thought I would share my little 2 cents