Just to add a little to the fact that some shooters hit too high, I've had quite a few instances over the years where client hunters have shot straight into the mouth of boar pigs when making a frontal shot.
The result being that the tusks are usually completely stuffed.
Another one is where the hunter is trying for a brain shot, the bullet goes high and blows a hunk of bristles and skin and bone off the top of a boars head.
Things often get exciting shortly after one of those shots!