Saw something today that I didn't really understand. In the box, away from the ball, a CAN CB football tackles a US FWD and basically lays her out. Then ball goes out of play over the end line. After a slight pause, a yellow card is issued to the CAN CB - no penalty. Play resumes with goal kick for CAN. What call is being made? If it is some sort of foul that merits cautioning, how is a penalty not given? Just confused and hoping some refs can shed light on this. Thanks.