A REBUILT backline shapes as a key weapon for St Kilda as its bids to return to the finals for the first time in six years.

In an interview with AFL.com.au, Saints coach Alan Richardson said the availability of Jake Carlisle after serving his 12-month WADA suspension and the recruitment of Collingwood premiership defender Nathan Brown will add flexibility as well as height to a unit that battled manfully in 2016 but conceded the sixth-most points in the competition.

Carlisle has spent time in the ruck and the forward line in match simulation, but come the start of the season, will be the defensive anchor of a side with high expectations.

"Part of our analysis of the gap between our best and our worst is that we rely heavily on team defence but you also have to get it done on your man at times," Richardson said. 

Carlisle at 198cm and Brown at 195cm represent upgrades on what the Saints have had before. Sam Fisher is now retired, but Richardson looks forward to deploying the likes of Sean Dempster and Sam Gilbert in different fashion.

"It gives us the opportunity to be unpredictable on game day and means we have more flexibility with Dempster and Gilbert, and with some of our running defenders. 

"We had 'Joey' (Leigh Montagna) behind the ball last year, Shane Savage has really improved, Bailey Rice has had a good pre-season, Brandon White, Jarryn Geary and Jimmy Webster will play there and Daniel McKenzie is nearly the best performer in the pre-season," he said. 

Team defence will remain the key at the Saints. "If we don't defend the ball and behind the ball then it won't matter. It's a real focus, but there are times to have to play one on one and get it done."

The Saints have brought in Jack Steele from Greater Western Sydney and Koby Stevens from the Western Bulldogs to bolster a midfield laden with talent, but it is the forward line that Richardson believes has the biggest scope for improvement. The combination of Paddy McCartin, Josh Bruce and Tim Membrey could feature for the Saints for years. 

McCartin struggled for continuity at times but has had a fine summer while Membrey enjoyed a breakout year in 2016, with 44 goals from 17 games including four bags of five majors. 

"We like the look of those three boys," Richardson said. "We think they're our future in front of the ball and we like what might happen at the fall of the ball with players like Jack Lonie, Darren Minchington, Jack Sinclair, Jade Gresham, Ben Long and Nathan Wright. 

"We have some real grunt and finish there, but it's a very young group." 

And then there's 34-year-old Nick Riewoldt, now of the midfield but still very much an ace up the sleeve for the coach. 

"As we saw in round 23 (when he kicked nine goals against the Brisbane Lions) we can chuck the old fella down there and he can still go pretty well," Richardson said.