Okay, I'll pose a few examples. If a rogue knows the critical points of a body and actively aims for these weak points get an increase in critical chance? I a duelist knows swordplay would they be better at parrying? Would a mage knows the science behind fire have better control over it?
It would help them know where they need to hit, but consider this: Some abilities are designed in such a way that you could hit anywhere and cripple them almost randomly. In that instance, sure knowing where to hit them for maximum damage would be helpful. But if your opponent also knows, then he's quite aware of what part of the body you're trying to hit and defend accordingly. Not to mention less obvious factors that are hard to discern at sight, such as one's DR which may allow them to survive said crit hit with no real issue. Sure normally hitting someone's bare and exposed hamstring would cripple them, but the armor is aesthetic: Even if it looks like a literal chainmail bikini, it's appearance is deceptive.
A duelist would be more used to parrying, and perhaps his avatar reflects this ability. But if that duelist happens to be a Mage in Deep Ground, the best he can do is try to apply his frankly weak physical skill against other warriors or rogues who not only have the raw stats to make a untrained swing dangerous, but may actually have the skills to make both a raw powerful and precise strike.
And magic is magic. That's hardly going to be closely defined and controlled by realistic physics beyond whatever would make it more interesting at the given moment (As ordained by the system I.e. Me).
The thing with Deep Ground is, it's one of those things where skills sometimes don't triumph over stats. You have to fight smart, sure, but that doesn't mean that you're better just because you know how to fight. It's like someone who's really good at digging holes with spoons. Others may be reliant on equipment or simply being strong enough to dig holes however they get, but this one guy can really dig a trench well with his spoon. But that doesn't mean he's the best at digging holes just because he can do it very well with a spoon. Some other people who don't really know how to use a shovel "Properly" will likely be able to do more anyways because they have a goddamn shovel, and your using a spoon of all things. And some of those guys DO know how to use a shovel, almost as much as you know how to use a spoon, which means they have bother better equipment and skills.
That's when you need to learn how to fight "smarter". Yeah, sure, it'll be good for a warrior to know how to actually fight. Use a stance, learn how to use a weapon. But he's assuming that everything can be beaten by using the same stance and the same weapon all the time. he may be a master swordsman, but if his only experience in fighting is against other guys with swords or no weapons, he's going to have a hard time against a rogue with a gun. Because most people don't have skills in parrying bullets. He needs to fight smarter, or if he doesn't want to do that, learn how to use a sword better. And he can only really learn how to block bullets in deep ground, cause as I've mentioned before, you simply can't do that in real life. No amount of real life training will prepare you to intentionally cut a bullet in the air. But such a thing is possible in Deep Ground. You just need... EXP.