the shoulder on a deer is a kind of flat bone, unless the arrow hits it straight on (square) it is very likely that it will not penatrate, i imagine he was up in a stand and shooting down, if he hit the shoulder bladethe arrow most likely deflected[&o], which is what sound to be the case, BTW i have killed a few deer that other people had shot with less than perfect shots, even founda broadhead in a deers hip once[:-]