Another is the unfortunate injury to lock Tom Donnelly, who strained a calf warming up at the start of the second half. Donnelly won't play again until the Hurricanes match in Wellington on April 18 at the earliest. After the Brumbies match the Blues have their first bye of the season.
The positives, though, are plentiful. There is a reason why Kirwan urged caution around expectations and that's because there will be real belief within the team that they are on the brink of something.
Chief among them is the defence, especially early in the match, which held strong despite enormous pressure from a Highlanders team including such backline threats as Ben Smith, Malakai Fekitoa and Patrick Osborne. "A lot of people would think a great try would really lift the team and it does, but just as important is being able to hold out the opposition for a long time," Kirwan said. "They threw the kitchen sink at us at the start and we held them out."
Watch: Rugby Highlights: Blues 30 Highlanders 12
The other is the set piece, a weak link for the Blues thus far.
"We really challenged the set piece this week. It's been wobbly. We won our lineouts, our scrum was very strong early in the game. They're just the fundamentals that we needed to get right. Let's not get carried away, we have to keep our feet on the ground. That game has to be a line in the sand for us from a performance point of view.
"We've got another huge game this week and it doesn't stop."
Kirwan will welcome back midfielder Francis Saili from his foot injury, though given the coach's cautious approach to re-introducing players, plus the performances of Nonu and Jackson Willison in the midfield, Saili is likely to get only a limited run from the reserves bench.
Veteran hooker Keven Mealamu will have a fitness test on his calf today, but lock Patrick Tuipulotu's knee will keep him out until the Hurricanes match at the earliest.
The return of Nonu and loose forward Jerome Kaino - who in playing 80 minutes stuck at it for longer than expected - have added a clinical edge not seen in the Blues' earlier performances and in Hayden Triggs, Kirwan has found a hard-working lock.