In the midst of the mayhem of the last quarter of St Kilda's elimination final against the Western Bulldogs, a calm head emerged for the Saints.

Nick Coffield, who has enjoyed a breakout third season with the Saints, stepped up to help his side to its three-point win, grabbing four intercept marks in a frantic last quarter as the Bulldogs made their charge.

The 20-year-old finished with eight grabs – five from the opposition's boot – from 16 disposals in his first AFL final to help the Saints progress to a semi-final clash with Richmond.

"We really like how he's been able to manage his opposition but have an influence in the game as well," Saints backline coach and former star Aaron Hamill told AFL.com.au.

"He's got the ability to not only get those possessions and take the heat out of the game but he's also quite creative."

Coffield is one of a defensive Saints trio that arrived at the club via the 2017 NAB AFL Draft and has underpinned part of the club's improvement this year.

The young defender finished fifth in this year's Trevor Barker Award on 119 votes after playing every game post-restart and also earned selection in the AFL Players' Association 22Under22 side.

Hunter Clark, who has become a St Kilda fan favourite already and looms as a long-term gun, was taken with pick No. 7 before the Saints swooped on Coffield with the next selection. But later in that draft the Saints also picked Ben Paton at No. 46, with Paton becoming a shutdown specialist, keeping a number of the game's best small forwards under wraps this year.

All three have been vital this season for the Saints, with Coffield's improvement obvious after his stints in the VFL last year. The attacking and clever half-back has played 17 games this season after eight last year.

"There's been no real surprise to see his development but it's been a bit of a slow burn for Nick," Hamill said.

"We're certainly seeing his growth. He's just scratched the surface in how good he can be."

The same applies for Clark, although his rise has been a little more linear. After playing 15 games in his debut season of 2018, he backed it up with 14 last year and has only missed one game this season, beginning to reveal his game-changing abilities as he switches between the half-back line and midfield.

"All those guys were drafted the same year but they've grown in different ways and at different times. Nothing fazes 'Hunts' too much, he just gets on with the job. You may not see it but internally he's driven and he's got high expectations of himself," Hamill said.

As the Saints' backline coach, Hamill joked that he's "hanging on for dear life" for Clark to remain in the defensive group, with exciting talent spending chunks of this season in a midfield role.

"We've seen him in the midfield often this year and I think going forward we'll see him in there a lot more, but he's creative and dynamic off half-back as well," he said.

Paton's development has perhaps been the surprise packet of the Saints' leap up the ladder.

The club's super stopper has closed down the likes of Sydney gun Tom Papley, Brisbane jet Charlie Cameron and Giants superstar Toby Greene in his coming-of-age season, rising from the backend of St Kilda's list to be one of its locks.

"That's been the biggest growth in him with his inner belief to get the jobs done," Hamill said.

"He's creative by foot, he's tough and hard and unconditional in the contest, and he's really getting the backline basics done."

The Saints' class of 2017 have not only graduated to be important members of the club's back half. They are tight off the field too, having spent plenty of time together in St Kilda's Noosa hub throughout this season, with Coffield even demanding a new nickname as the year has progressed.

"These guys are going to play a lot of footy together for a number of year and are going to have sustained success hopefully. They're a great group. They absorb a lot of information but importantly they're getting the job done," Hamill said.

"They enjoy each other's company, hanging a bit of crap on each other. 'Coff' gives us a little laugh. He likes to be called 'The Coff', I'm not sure where that came from but we're running with it. Coff doesn't answer to 'Coff' any more, just 'The Coff'. The boys are having a little bit of a laugh with that."