Its very hard to get "just" brisket on a quartering away shot.

Most of the time a brisket shot is evident from a larde amount of tallow on the arrow (white slimy substance).

White hairs almost always mean one of the holes is low.

Don't let the "she will live thoughts" enter your head.

If it is thick - look carefully at low branches and brush for blood. If it doesn't make it to the ground it will smear on these low branches.