Board Thread:Episode Discussions/@comment-1251315-20161215125344/@comment-25122992-20161216184109

No, if concentration really matters, he must know what he concentrates for. Otherwise, it means the durability works unconsciously. Naruto wasn't concentrating on anything back then. In his normal state, he would take the damage regardless if he's prepared or not, and Naruto must've known it, unlike the fact he won't receive any injuries in SM state.