CHRIS Fagan has made some tough decisions in the past 12 months, but perhaps the most crucial was one that went under the radar at the start of last off-season.

After his team was humbled by Geelong to the tune of 71 points in the preliminary final, Brisbane's coach realised doing things the same way was likely to lead to the same result.

So, while Dom Ambrogio and his list management team went about re-stocking the player cupboard with Josh Dunkley, Jack Gunston, Will Ashcroft, Jaspa Fletcher and Conor McKenna during the trade, free agency and draft period, Fagan started to tinker with his football department.

Murray Davis had coached the Lions backline for a decade, while Jed Adcock had been the forward line coach for the past six seasons.

Searching for something new, Fagan switched them over, moving Davis to the forward line and Adcock back.

Although Fagan is reluctant to attribute the switch-up to Brisbane's improved team defence in 2023 – he rightly says any structural or game plan changes are a collective approach rather than an individual line coach taking charge of his area - the players certainly believe it has made a difference, even if its only been a small one.

And when you've made a semi-final or preliminary final four years straight like the Lions have, even a minuscule improvement can take you all the way to a premiership.

Half-forward Lincoln McCarthy, who is expected to return from a calf injury for Saturday night's qualifying final against Port Adelaide, recently conceded there was no obvious reason for the coaching switch, but said it had made an impact.

"It was just a change-up," McCarthy said. "It was just a good freshen up for everyone.

"It's been really good for the coaches and really good for the players."

The adjustment during the pre-season was obvious, with Brisbane doing a stack of drills on its new Brighton Homes Arena surface focusing on team defence.

The defensive team in these drills would work collectively to one side of the field to thwart the attacking team, before a second ball would suddenly get kicked in from the opposite wing, forcing the defenders to hustle to the other side and pick-up a new team of attackers. It was taxing work in Brisbane's searing heat.

Davis was in the ear of his new forward group reminding them they were the front line of defence, and Adcock was encouraging the defenders to be more proactive, knowing pressure was going to be hotter up the ground.

The results have followed.

After conceding 82 points a game in 2022 to be ranked 10th defensively, Brisbane has improved almost a goal a game to climb all the way to sixth. Small increments, big results.

As ever, Charlie Cameron has been a constant threat up forward, executing 42 tackles inside forward 50 to finish the year tied for second in that category, just one behind Kysaiah Pickett.

McCarthy has also played a selfless role, flying for less marks than previous years and being prepared to wait at ground level to either crumb the loose ball or provide the first defensive layer.

Co-captain Harris Andrews, who still does his captain's run 'extras' and pre-game warm-up with Davis, recently told AFL.com.au that Adcock had made a big impression on him in articulating the system the Lions wanted to play.

"We spent a lot of time over summer working on team defence ... there was a massive emphasis on that," he said.

"What can happen now is you can be a bit more proactive, and you can think quicker and not just rely on physical attributes.

"You can work on the mental side and anticipate what's happening and that's probably helped me.

"Maybe in the past we were a bit more on one-on-one, where you rely on your physical attributes. There's so many great forwards that have great physical attributes and you can't always beat them that way."

While their defence has tightened up, scoring has remained a strength of the Lions with Davis in charge of the front third. Only Adelaide, who cashed in with a hefty round 24 win over West Coast, scored more heavily during the home-and-away season.

Fagan has had some tough decisions to make this year, none moreso than telling veterans Daniel Rich and Jack Gunston they needed to sit out a month of senior footy to get fit (despite what he said publicly to protect the players).

However, don't discount the value of his choice to switch the line coaches and the impact it has had on a Brisbane team trying to win its first premiership in two decades.