I didn’t go through ALL the comments to see if this was mentioned but I went through a lot of them.
This injury explains, partly, the multiple shots the officer took and the wound pattern, which was all over the place. His vision had to be impaired especially if it was his dominant eye used to aim his firearm. The other part of the explanation is the size, momentum and determination of Mike Brown.
I think Brown had his arms crossed over his belly. The cop did go for the mass.