Reading the OP and the case play, I don't think we really have a definitive answer. This is a case of where the B player went OOB and picked up the ball. The case play only says what to do when they reach through the boundary and pick it up. What about if she comes OOB without reaching through the boundary, and picks up the ball? You can't issue a warning there because she's not reaching through the boundary per se. I'll just sit back with my popcorn and listen to the comments fly.