Who's to say that in Calum Murrays opinion Papac wasn't seriously injured? Where they are in the pitch increases/decreases the likelihood of play being stopped. If the exact same thing happened in the middle of the park, I have no doubts that the game would have been stopped straight away. It shouldn't happen that way, but it does. If that was Mark Wilson who had cleared the ball off the line and fell back clutching his head, would you want play to be stopped if Rangers had a clear shot on goal?