This was the beginning of his response to a question about his decision to continue attacking when his side had secured a 1-0 lead through Mary Fowler and produced a dominant first half.
Gustavsson revealed that three substitutions would need to be made on the advice of the sports science and medicine team and so the question followed that knowing that, why did he choose to play the cards he did?
"We coaches are paid to make decisions before we know if they're right or wrong and afterwards," Gustavsson explained. "It's very easy to say: 'Why didn't you do that?'
"We're paid to make those decisions pre-knowing what's right and wrong."
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He went on to elaborate that if his team had instead focused on keeping that 1-0 lead, practising game management, and had still gone on to concede two goals, the question could well have been reversed but with the same answer.
It's hardly a revelation that coaches must hypothesise on how best to solve any problem to win any given game and that, with the law of averages, they are likely to get it wrong as often as they get it right.
But the sentiment of his answer, of not knowing how something will turn out until all is said and done, and only knowing with certainty that one course of action was better than the other based on the known outcome, feels more pertinent than ever at this specific moment in the Matildas' journey to a home World Cup in 2023.
And it extends far beyond the decision to park the bus or keep attacking in a friendly game against Canada.
Gustavsson's entire tenure -- and his appointment in the first place -- has been built on decisions that he believes will pan out in the long term, both in terms of player development and actual footballing output, culminating in that World Cup on home soil. It's only with hindsight that the clearest picture of whether his decisions were the right ones will be revealed.
And these decisions vary wildly. There's the difficulty of the schedule and opponents that he and Football Australia have pursued in preparation for the World Cup. There's which players are deployed where and given minutes over others. And then there's deciding which game management style to pursue, not necessarily knowing that Adriana Leon was about to continue her Australian love affair with another two goals.
So as Gustavsson sat in the press conference after the Matildas had been resigned to back-to-back defeats, he explained his decisions, speaking to the belief he and the team have in what they are doing, and asking fans to acknowledge the improvement and hold their nerve a little bit longer.
He had done all of these things before but never with less goodwill in the bank.
"It's frustrating because we felt those first 45 minutes were maybe the first time in a very long time, where we performed consistently for 45 minutes in a row. We've seen patches before, as I've spoken about, five minutes here, seven minutes there," he said.
"This was 45 minutes of complete performance, where we were actually dominating Canada, Olympic champions, and we had six starters from the Olympics, not even available going into the game and that felt so good.
"I hope that those outside saw some improvement in terms of the fact that we can dominate the top team, not just compete with them. I hope that can be looked upon as an improvement and also to be able to do that with six key players out."
To deny any sort of improvement in the team would be unfair.
The proof was in the pudding in the first half against Canada. Cortnee Vine and Caitlin Foord contributed to one of the most exciting and dynamic front three performances from an Australian side in some time.
Katrina Gorry continues to grow into her role as the quarterbacking No. 6, offering up one of her most assured defensive outings in the opening 45 in addition to the expected attacking prowess. Charli Grant's development as a right-back seems to accelerate with every passing game thanks to the opportunity presented by Ellie Carpenter's injury.
The players felt it too. Foord's comments post-game felt telling.
"How it looked is how it felt for us as well. We felt like we were dominating, we felt like it felt like us again," she told media when asked about the first half.
It bears repeating: The Matildas felt like the Matildas again.
To single out the quote could be seen as reading too much into it if not for the fact that the Matildas did indeed look like the Matildas again. Quick, dynamic, exciting.
It was the football that was promised in the Gustavsson era: Attacking, aggressive, dominant. Australia's lone goal came through Fowler in the third minute and, at the time, felt like it was a tone setter for what was to come for the rest of the match, not just a half.
But therein lies why many fans feel so agitated. One half of the football that was promised plus the crumbs of good football seen previously don't offer a strong indication that things are moving in the direction they need to as quickly as they need to.
This isn't to say it won't -- stranger things have happened in football -- but the timeline as it stands now makes it feel that little bit more impossible.
Time feels like it is running out because it is by Gustavsson's own admission right before this friendly series started. Things have to start happening.
So now, just like a coach is unsure if the decision that was made was the right call until after the fact, Football Australia arguably find themselves in that exact same boat.
Two paths are laid out before the federation and a decision ultimately has to be made, without knowing whether it is right or not.
Football Australia has thus far stood by their man and may well continue to do so. It could pan out well, with improvement accelerating over the next nine months and the Matildas achieving the success they have defined for themselves.
It could also pan out horribly, with time not being kind, the improvements continuing at a glacial pace, or even worse slowing down further, and the Matildas failing to reach even the bare minimum KPIs come 2023.
Football Australia could just as easily pull the plug now. Cite the eight wins, five draws, and 13 losses as reason enough to move on to something new. That would of course require finding someone else available and ready to take on this high pressure gig and make things happen in a ridiculously small amount of time.
That decision in turn could see the Matildas reach the heights they desire in which Gustavsson's sacking would be justified. If they still do not achieve what is demanded then perhaps the timings of the decision will be highlighted and used as an excuse. Perhaps there will be sympathy for Gustavsson in this potential future, too.
All of this is to say that decisions must be made before it is known whether they are right or wrong. The grey area in between feels like it doesn't exist.
But the timeline and the results demand that a decision be made either way. The Australian footballing public will then wait to critique with the clarity of hindsight as to the validity of the decisions.
And with only 25 days until the October window, the decision needs to be made now.