Well the first big thing that I took from it is the use of illegal moves and targets. Some of the main targets in krav are things like the knee caps, the groin and the back of the head. These areas are never targeted in sports martial arts, but they are some of the best areas to target if you want to disable an attacker quickly and efficiently. In the same way that a change in rules allowing kicks below the waist completely changes the dynamics of how you have to approach kickboxing, having new targets available changes how a street fight should be best approached. In with that comes stuff like eye attacks and gouges, limb destructions, headbutts and so on.

The obvious question after that is probably 'well why not still just do kickboxing and wrestling, then just do that stuff when you get attacked?'. The thing is in a high adrenaline situation like a street fight you'll do what's been practised into a reflex. If you're a boxer, you probably won't throw kicks or try and wrestle, and if you've not practised fighting dirty, you probably won't to that either, even if it's the most efficient option.

The other thing is that even with moves like an eye gouge, there's a right and a wrong way to do it and a right and wrong time. It's the same with any kind of move. A very obvious example of this that everyone has encountered is headbutts. Everyone's seen a shit headbutt in their time. There are a good few effective ways to use it, but a lot of people who attempt it end up doing more harm to themselves than the other person. There's a right and a wrong way to fight dirty basically.