Actually,
A slightly quartering away shot is preferable to a broadside shot in most hunters that have been bowhunting for any significant amount of time. Slightly quartering away gives you more room for error, plus the ability to get some liver, both lungs and the top of the heart with one shot. Miss a little back, you still get liver and lung. A little forward, still both lungs.

Quartering towards you, now that can be a problematic shot, especially at any distance or acute angle at all. When quarteringtowards you itis generally best to waittill you get a broadside or quartering away. Also, quartering towards can end up deflecting an arrow as the ribs tend to be more of an obstacle at this angle. I have heard of mechanicals failing miserably on this shot.

Deer can do some amazing things. My guess is that the deer movedwhile the arrow was on the way and even on impact. I had a doe at 30 yards last week almost turn inside out trying to jump the string. I shoot a Switchback XT and it is very quiet and pretty fast. She still went from broadside to quartering towards me in the amount of time it took the arrow to get to her. Instead of a broadside punch through, it went in, hit a lung and liver and ended up with the broadhead in the opposite back hip bone. Lots of blood and only about an 80 yard track.
R
Hank