B with foot OOB

[rainmaker]

On a thread started earlier, there was a question about legal guarding position with one foot out of bounds. It occurs to me that if this guard gets a hand on the ball, then the ball has gone OOB and A gets a throw-in. Would that be good strategy for the B team to practice? It would be a great way to stop a drive without an intentional foul. IF the ref would call it correctly. Or is it illegal? Or what?