we all know that kakashi is one badass shinobi, and can own the majority of jounin from all villages. but when he encountered oro during the prelims, they made him seem like nothing.
however, later on when itachi appears, he's able to hold off that shark dude (forgot his name), and with just a kagebunshin which has half the normal chakra (Im not sure if it was mentioned, or if i just imagined it, but i think that shark guy is as strong as, if not stronger then oro). And at the same time, he faced itachi and fared pretty well imo (up untill itachi whiped out his sharingan). if it hadn't been for the mangekyo (sp) sharingan, i think kakashi could've atleast held itachi till ANBU arrived.....and thats no small feat.
granted that after the his "fight" with kabuto he trained to get back in shape, but he couldn't have improved enuff to all of a sudden be a match for S-rank criminals.
so, do u think we've seen kakashi's true strength yet? after all, he is a famous ninja feard by many shinobi and he keeps surprising us by taking on strong and stronger opponents.