Kirwan, the Blues coaching group and players spent several hours yesterday dissecting video replays and analysing the flaws in their 21-28 loss to the Bulls.
The squad have been dismissed until next week with weights and training plans for their bye round until they regroup for their next match against the Waratahs.
"We did not lose because of the selection changes or inexperience," Kirwan said. "We lost because we weren't ready for the intensity - just as the Chiefs and Highlanders discovered against their African rivals.
"You have to have a mindset for these games. Hats off to the Bulls. While we were ordinary, we have no one else to blame."
The next block of games for the Blues, before their second bye, does not offer much respite.
They travel away to the Waratahs and Chiefs before they host the Highlanders and a repeat meeting with the Hurricanes.
Kirwan liked the way his side hung on against the Bulls and with their bye this round he noted they would have 15 points from a possible 20. That was encouraging and other sides would envy that tally.
When they played well, the Blues had created some chances and scored tries. They just did not deliver often enough and that was an issue about mental preparation.
"We were probably 5 per cent off.. Some of the mistakes they made were because they had never been in these situations before.
"We did not tough out a win playing badly, which is something you have to learn. The Bulls were strong at manipulating us at the right times."
A number of the newer players improved as the game went on but young utility Albert Nikoro has damaged his shoulder and will miss three weeks.
The Waratahs would be a huge contest.
Suggestions some in the inexperienced Blues group might have been complacent or overconfident after two victories did not wash with Kirwan.
He thought the failure occurred because of a number of factors like their uncertainty about preparing for such a different direct challenge from the brutal Bulls. Young players thought they were ready but they had not made sure.
"This will be a loss if we don't learn from it, the best thing will be if we take the lessons out of it," Kirwan said.
"When the boys come back I want them to start like this is a new season and they have to be refreshed. We have to explode into the Waratahs because it is a huge game. This setback has already been put to bed. They missed an opportunity but we did not get beaten badly and could have done so much better."
Former skipper Keven Mealamu sat in on yesterday's session and will return fulltime next week when the demands on the Blues will be about energy and accuracy for their trip across the Ditch.
SA supremacy?
2013 cross-border clashes
Sth Africa 3 NZ 1
Australia 1 NZ 0
Sth Africa 2 Australia 0
In five matches against other franchises, the Chiefs' 45-3 win against the Cheetahs remains NZ's only victory.
