This is how i see it.
I've seen a scrap or two, and even been in a few, and when someone has a jacket or sweater on, it's a good bet it'll be pulled on and crawl up the back.
I had this happen before, and i got fed up with it being over my head, so i pulled it off and threw it.
A hoodie is even worse, and that light grey shirt Martin was wearing underneath, would look just like a white shirt when there's low light conditions.
At first glance, #3 might have only been able to see that white shirt, until the movement outlined the activity.