This should be possible in multi-player. I can think of a couple of ways they might have achieved this effect in BM:
- Somehow firing decals at the player's view model.
- Switching to an alternate "bloody" version of the weapon skin.
I think the 1st is more likely as I seem to recall the splatter pattern looked the same for all weapons and that it faded out over time.
If I were to do something like this, I would be more inclined to make it part of the HUD, like CODs "jam in the eyes" effect.
I'm not actually planning on doing either of these, but I have given some thought as to how it could be done.