While there are a number of reasons for the Brisbane Lions' improvement in 2018, its markedly superior defence has to be close to the top of the list.

The Lions are conceding a staggering 40 points less each game than they were two seasons ago.

In 2016 they were historically one of the worst defensive teams in history, giving up 131 points each game.

Last year – Chris Fagan's first in charge – that number reduced to 115 points per game, and through 16 rounds this season, it's down to 91.

Although it's far too simplistic to give all the credit for that improvement to the defensive unit, that's unquestionably where most of the plaudits should lie.

The forward line and midfield get a tick for helping to reduce the number of inside 50s conceded from 62 to 55 in that period, and the team's more competent ball movement has reduced the simple turnover goals that previously dogged the Lions.

But after implementing a largely one-on-one system for the first three quarters of last season, Fagan has successfully installed a full ground press that characterises the best team defence.

Ryan Lester recently told the Club's podcast 'The Roar Deal' that Luke Hodge deserved a lot of credit for both educating the defenders and instilling confidence in them.

Veteran Daniel Rich told AFL.com.au defensive coach Murray Davis was also a huge reason behind the improvement.

"We're a tight bunch back there, that's for sure," Rich said.

"We train together hard and firm and have high expectations on each other, and that's flowing on to the field.

"We have that brotherhood approach back there."

Rich has been one of Fagan's major success stories as a reclamation project, turning the gifted left-footer from frustratingly inconsistent player to a reliable half-back that is as tough as he is creative.

Harris Andrews was in All Australian contention before being concussed against the Giants, Darcy Gardiner is one of the most improved players in the AFL, Nick Robertson has found a home and Alex Witherden has continued to flourish in his second season.

"That individual improvement you guys see is on the back of playing better as a team and a unit," Rich said.

"There's a difference between 55 good looks and 55 rushed kicks coming inside 50.

"As a back seven we value how those kicks are coming in – we owe a lot to those guys up the field.

"There's been growth to us seven guys, and the guys in the NEAFL putting pressure on.

"There's nothing better than seeing one of the big boys fly across and punch the ball out of bounds. I get a kick out of that. it's a sign of the mindset we have back there."

Without Andrews – the team's vice-captain – over the past three weeks, and Hodge last week (and this) with a calf injury, much of the recognised leadership has been sidelined.

With Lester playing his best football for the season and Josh Walker seamlessly stepping in to replace Andrews, Fagan said he had learnt even more about the men he entrusted to stop goals.

"I've learnt those two boys (Andrews and Hodge) have done a good job at teaching the other lads how to look after themselves, set up structures," he said.

"It was really pleasing to see that.

"You don't want a team that when one or two players go out, everything falls apart.

"Injuries do come along. Last week and the last three that Harris has been out, we've been able to cope."

But with Andrews available next week, and possibly Hodge, for the first time in Fagan's coaching career he might have some genuinely difficult calls to make at team selection.