Ball thrown off defender

[frezer11]

Here's the situation:

GV game, Player A1 is inbounding under the hoop, and B1 is lined up across, but not facing her (so as to watch the cuts of defenders and react, etc.) The count gets to about 4 when A1 realizes she has to do something and throws it off the defenders back and out of bounds, as we've all probably seen before. But here's the thing: A1 throws the ball overhand baseball style about as hard as she can into the middle of B1's back. We were sort of taken by surprise, but there's nothing illegal about it, so whatever. About 5 minutes later, exact same A1 does the exact same thing, and the coach of the defending team perks about "Come on, no way she can do that?!!"

I'll post what we did about it a little later on, but I'd like to get some input as to what, if anything, any of you would do first. While we realize that no rule was violated, and throwing the ball off the defender is a perfectly legal and acceptable strategy, the force with which the ball was thrown at a defender less than 5 feet away was clearly unneccessary. Let me know what you all think-