Well relying on any kind of striking is out then. So much for all the muay thai and boxing I've done. Really though, groin strikes tend to work very well, unless you hit like a 12 year old girl.
What is it that makes 12 year old girls impervious to groin attacks--does the onset of puberty increase their resistence?
Seriously though, the issue here isn't that 'groin attacks never work', it's that relying on a single 'fight ending' blow is not good s.d. training imo. A lot of techniques I've seen in krav involve a pulled kick to the groin and the person playing attacker acting as though they are really injured, bending down, whatever, so that the technique chain can be finished. I'm not saying that krav maga wouldn't have a response to missing the groin, or the groin attack not actually doing anything, just that what is out there doesn't show this reality. Considering krav's claim to fame is RBSD, I find this odd.
Neither boxing or MT training is predicated on a single fight ending blow. That is the goal, sure, but techniques are taught in a manner where if that blow is unsuccesful, you can launch the next one. If fight ending blows were so easy to attain, I hardly think either of these arts would be interesting spectator sports--they would be over in seconds. So one question I have is...why does a MT match often take so long to acheive a knock out (if it indeed does), whereas RBSD systems show the fight ending in seconds? Which one is more realistic? Is the truth somewhere inbetween?
Basically, all I'm saying is to check the assumptions that go into techniques. If the assumption of your technique is that this one blow will 'finish' your opponent, well, I don't think that's so good. If it's 'this might do this, but if not here's how to flow into something else', then that's good.
Seriously though, if a guy is coming at you and he looks hopped up on drugs or something, not much of any martial arts is likely to work, grab the nearest available weapon. Survive first, deal with the law later. Hard drugs should be considered deadly weapons. I've heard of guys who looked completely gone with various things taking multiple gun shots and continuing to fight. Yeah like any unarmed fighting is really going to work.
You are right, in this situation most unarmed fighting won't work. Nonetheless, I think this is the situation you should train for because it increases your 'b.s. threshold'. Train with an eye to beating this guy and suddenly a lot of crap that gets taught goes out the window. I know that sounds a little contradictory, but basically what I'm saying is that the single most important assumption underlying all s.d. training should be that the attacker is well trained and willing to inflict severe violence with no regard to rules, laws etc. and has a very high pain threshold.