please explain the logic behind this (spoilers )

just beet the network guardian that giant strogg beet him realy easy he does hardly any damage then played bit more and cum up against one of them flying things and he got homing missiles that home round corners and everything witch is annoying then he just shoots me 2 or 3 times and im dead seriously ( i was at full health 125 ) the network guardian does less damage than this lil guy and the flying guy servided 3 shots form the dark matter gun how the hell so how does it work that a lil fat flying thing is more powerful than a boss