I'd love to hear from those more knowledgeable on the subject but my guess is he was shot with an improperly tuned bow/arrow combination.
I had a friend who had owned a bow for a LONG time, and hunted with it occasionally. He shot a great buck with it and got very poor penetration. The deer survived and was back on camera a few weeks later.
Our analysis concluded that that arrow was whipping back and forth as it hit the deer. Based on his recollection of what he observed on the shot, and there only being blood on the first few inches of the arrow, we felt the whipping resulted in the broadhead penetrating slightly and the majority of the arrow shaft slapping up against the deer's body. (This was a number of years ago and I don't recall whether the arrow broke or not, seems like it did.)
Fortunately he went to a good archery shop and bought a new bow after that experience.
I had a friend who had owned a bow for a LONG time, and hunted with it occasionally. He shot a great buck with it and got very poor penetration. The deer survived and was back on camera a few weeks later.
Our analysis concluded that that arrow was whipping back and forth as it hit the deer. Based on his recollection of what he observed on the shot, and there only being blood on the first few inches of the arrow, we felt the whipping resulted in the broadhead penetrating slightly and the majority of the arrow shaft slapping up against the deer's body. (This was a number of years ago and I don't recall whether the arrow broke or not, seems like it did.)
Fortunately he went to a good archery shop and bought a new bow after that experience.

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