A defenseless player is one who because of their physical position and focus of concentration is especially vulnerable to injury. When in question, a player is defenseless, an example of a defenseless player is not limited to:
A. A player in the act or just after the act of throwing a pass. This includes a player in passing posture with focus downfield.
This is just bad. So if a player is throwing the football, the ball is still in his hand, and you hit him from his blind side that is a roughing call.