Hansen, who was a relieved man after his side beat the Irish 22-19 thanks to a last-minute drop goal, said the great strength of New Zealand rugby - wanting to move the ball round and use every player on the field - probably came back to haunt the All Blacks on Saturday night.
But he pointed to some great character shown by players in the final minutes and a desire to win, despite the side making too many mistakes.
"It was a game we probably should not have won. But the character of the team came through and the composure at the end allowed us to do that.
"We will learn a heck of a lot from this test match for the week ahead. Maybe we thought we had prepared well but I don't think we have, in reflection.
"You just don't give away stupid penalties like tonight if you are in the right zone.
"I think our game under the conditions ... we may have been a bit naive at times and tried to play too much rugby in our own half.
"The All Blacks are often guilty of that and that is because we play rugby. Our great strength is the 15 people on the park. It is just a little bit of fine-tuning and understanding how to use the conditions to support the team you have got."
Hansen admitted the All Blacks were lucky to win, and suffered from mistakes at key times.
"The pleasing thing was we played an Irish side which probably played as good as it could have.
"We have not played great but we have showed a tremendous amount of character to play smart rugby to drop a goal in the last 30 seconds of a game to win."
Hansen could not remember the last time the All Blacks won a game with a drop goal. But he remembered one they had not - the 2006 World Cup quarterfinal against France.
The All Blacks met a fired-up Irish side on Saturday night, one bearing little resemblance to the inaccurate, sloppy mob that was convincingly outplayed in Auckland last week.
All Black captain Richie McCaw said, while his side had not played well, it had to be happy with the way it managed to set up for the winning drop goal.
"We had to keep believing . . . obviously we went down the right end of the field.
"We would have liked to have been in a better position than that but we weren't and we managed to get that drop goal was the key.
"Composure is a big thing," McCaw said.
"They brought a fair bit of intensity that you expect in test matches. And they definitely played well.
"Straight after halftime, when we scored a try, it looked like we were getting on top but a couple of mistakes, one after the other, gave the momentum back to them.
"You could see them lift and they are not a bad side when they have that momentum."
Hansen admitted his players would have learnt from the game, and made aware how difficult test rugby is, and the standards expected.
"Plenty of young men and older men have been reminded of what test rugby is all about.
"We will go away having learnt plenty from this game and knowing we have lots to work on."
All Black lock Ali Williams is to undergo knee surgery and will be out of rugby for at least eight weeks.
A scan has revealed he has a flap of loose articular cartilage, which will require surgery. He will see a surgeon this week in Auckland.
The injury is in the same knee which Williams had an operation on in the off-season, but Dr Debbie Robinson said it was a new injury.
Chiefs loose forward Liam Messam is to join the All Blacks as a replacement player. Lock Luke Romano will likely join the bench for the final test.
No 8 Kieran Read left the field at halftime after a knock to the head, but Hansen said he appeared to be fine after the match.
Blindside flanker Adam Thomson was in the wars all night, and got a smack on a nose which was already broken.
Irish captain Brian O'Driscoll was disappointed with the loss but proud of the performance of his side.
He felt the side had let itself down last week in Auckland and had standards to maintain.
The Irish jersey deserved more, he said, and the team just wanted to keep playing throughout the 80 minutes.
