He stepped into a role that had tripped up some big names through the years from coaches like Peter Sloane, David Nucifora, Pat Lam, Sir John Kirwan and Tana Umaga to bring home the first prize since 2003.
The former Crusaders player and coach who enjoyed Super Rugby championship success said it was a special moment.
MacDonald said the win meant a huge amount because there had been a risk in shifting his family to Auckland, away from the environment they knew to one they didn't. He also had to work with players who were not familiar with him.
"When I see the boys faces out there on the grass, there was quite a few emotional guys who have been around this club for a long time and who have seen a lot of pain, it just meant so much to them," he said.
It was life-changing for some players who had only dreamed of winning titles before, and that was the motivation and reward for him.
But as with any campaign, more changes lie ahead.
More players announced their departures from the side after the win. Lock Gerald Cowley-Tuioti and second five-eighths TJ Faiane had earlier said they would be playing their last games. But first five-eighths Otere Black is leaving for Japan, and flanker Blake Gibson is moving to another franchise.
However, MacDonald said they were pretty well settled on their squad for next year with Beauden Barrett returning and New Zealand rugby league star Roger Tuivasa-Sheck joining the side.
He said he had no thought of where Tuivasa-Sheck would slot into the side. It was important that he played first, and it was likely that will be with Auckland in the national provincial championship.
He said Zarn Sullivan was likely to continue, in the meantime, at fullback, where he was developing well. Barrett was back, Stephen Perofeta was playing good rugby, and Harry Plummer had stepped up to the mark, so they had good depth in the position.
There were one or two vacant spots. Chief executive Andrew Hore said the consideration was getting the balance right between young and old in the group.
He cited fullback Zarn Sullivan as the type of younger player they now had available.
MacDonald said Sullivan had filled a Barrett-type role for the side during the year by providing kicking options with his strong left-boot.
"It's an important part of our game getting that kick-balance right because of our big men. We ask them to scrum then, we ask them to tackle their hearts out, then we can't run them around by chucking the ball everywhere, so Zarn has been really good in that space.
"He's been physical and, I thought, our back three has become one of the most physical in the competition, Bryce [Heem] in particular has led the way there, and Mark [Telea] has come back after being dropped and brought a real edge.
"It's so pleasing to see young guys like that [Sullivan] step up in the big time. He's enjoying himself, he's got a lot to offer and he's just starting," he said.
MacDonald said from the time he first came into his coaching role, he realised the Blues needed to be a fitter team.
"We're naturally quite a big team, we've got big athletes," he said.
That meant they needed to be able to play long minutes, or big minutes, and then back that up a week later, and that required building up the conditioning of the side.
Better game understanding, and game leadership, also played a big part in the side's advance.
"Every week we've been really driving our leadership and Paddy's [Tuipulotu] jumped into that void and he's been well supported with a lot of meetings and a lot of conversations around all types of leadership on and off the grass," he said.
Those outcomes were reflected in many ways but were seen in their game management, under pressure, during the final.
"We didn't get it perfect but at times we made some good, smart plays where we pinned them in the corners, we contested the breakdowns, we put pressure in the air at the lineout and we did the small things well," he said.
Blues chief executive Andrew Hore said the last 18 months, and especially the way they were hit in 2020, when a prospective full house for the last Super Rugby Aotearoa game, against the Crusaders, was called off, while at the beginning of 2021, people were tired after Covid lockdowns.
"The city and the region is probably tired, it's probably been hit the most. We understand we've got an obligation to the wider Blues community, and it is just great to have rugby clubs, hopefully, benefit from this.
"It's fantastic, so we're absolutely delighted. There's been a lot of hard work gone in from a lot of people to have a vision of where we wanted to get to. We still know we've got [more] to go, and that's the exciting part," he said.
Hore said attracting a big crowd on Saturday gave the Blues some stability, especially in a time of great change. It was important any reserves they had, were put into the right areas.
That increased the pressure on the administrators to make the right moves.
The win was also important because they are looking at a strategic plan.
He had come into his role and gone into a lockdown and survival mode. But now, they could look at recovery mode, and the win gave them some breathing space while thinking through their process.
Hore said the beauty of having a big crowd was seeing that there was a belief, even as the Highlanders upped the pressure and clawed their way ahead, that the Blues could still come through. In the past, that hadn't happened, but it was clear from the reaction that fans had more faith.