User blog comment:Silva-zoldyck/what if... they caught annie before transforming?/@comment-68.80.160.104-20130926023539/@comment-7418318-20130926093355

Remember how not even Levi's squad was told about the Annia-capture operation and it was later revealed that only those were told who already served before Shiganshima fell? That means those four were soldiers for less than five years. Levi on the other hand was already famous at that point and thus most likely a veteran even then, which gives him quite a lot more experience than those four. So he's not only a natural talent, but also very experienced on top, which explaines how he can be so much stronger than even his elite squad members.

Mikasa on the other hand does not seem entirely a "normal Human" to me.

As a nine year old child she showed one burst of power that allowed her to crush the wooden handle of the knife with just one hand and stomp down hard enough to crack the wood-floor. Unless the wood of both the knife handle and floor were partially decayed that's something not even a very strong adult should be able to do, much less an untrained 9 year old girl.