A guy near my wife's family's vineyard was out at the pig pen yesterday. The 150 kilo mangalica male got out of the pen and was trying to get into the pen with the sows.I remember reading about hippos in Africa, and it explained that you never want to get between the hippos and the water, nor between a hippo cow and her calf. If you do, you risk getting killed by a hippo.
The owner tried to usher him back in per usual, whatever that means, and the pig went nuts and attacked, knocked him down, bit his legs and was going for the grown and belly areas. The owner fended him off but one of the bites, or maybe two, severed an artery in the thigh.
With boars, you never want to get between them and the sows in heat. Like hippos, boars are aggressive, unpredictable and not afraid of you.
Boars have evolved to fight off competitors and breed sows. When the boar experiences the females in heat, he gets ready to fight and breed those sows. When the human gets in there to try to get the boar away from the sows, the boar may choose to fight instead of yielding.
If this incident really involved a loose boar and some sows in heat, it isn't so surprising the guy got attacked. He just seems to have been particularly unlucky and got a lethal bite.
There's probably two other mitigating factors:
1) The boar probably was like family pet. The owner trusted it a bit too much. Had the boar just been yet another pig, he probably would have been more wary.
2) The owner didn't have a proper enclosure to keep the boar. Had the boar been on a bigger farm, it probably would have been better contained. That's because although is possible to run small number of pigs with flimsy facilities, you can't run a big farm that way.