What do you do?

[youngump]

Originally Posted by MD Longhorn

You would have no rules basis for such a ruling.

Would you treat it the same if F4 was distracted by an errant cup that flew over from another field? A leaf? A bird or bee? Dust? A loud cheer? Why would a ball be different from the rest of these?

Well you do if you call it spectator interference. Though whether you can seems less clear. If the fans of the other team threw a medicine ball at the fielder intentionally you'd call it interference right? What if they intentionally threw a softball? So the only difference here is that they weren't watching the game and they didn't do it on purpose. That may be enough to hang your hat on, but I think the spirit of the spectator interference rule was to neutralize non-participants impact on the game. I could be very wrong though.