It looked like my arrow was 1/3 in him. Maybe 10 inches or so.
With you being above him and your shot angled downward you very likely took out the front of the lung and possibly the trachea as well. Whenyou go back out to look for him, pay attention up high as well. Not all the blood makes it to the ground, especially when you get one lung. I just shot a buck last week in very nearly the same place and though I only thought I got about 10"-12" penetration, it was enough to lodge the broadhead in the off shoulder. I'd say he's dead somewhere.
Good luck!
GH