All animes with some kind of super power or techniques or how ever it is called create their own kind of 'realism', they use throughout the show. The problem here is, that the fight is not convincing concerning the shows own 'realsim'. And of course it is not Naruto, but Sasuke leading to this impression. Sasuke just took too much hits and used too damn much chakra ( 2 chidoris and a whole bunch of fire ninjutsus) for his normal self without even using the seal and showed no signs of damage or just fatigue