sirebors

This... Oh and no ring for Sammy

I'm actually curious what the boundary is between a good play and a penalty. Can a player attempt to punch a ball out, miss, and strike that player in the chest, or arm, or head? How is punching someone under the guise of going for the ball still legal? I want to know the actual difference or the cut off boundary that it would be called a penalty. If Jerry Hughes did that exact same thing to Tom Brady and missed the ball and struck Brady in the chest would he be flagged?