NORTH Melbourne skipper Adam Simpson says the Roos must improve their squad's depth if they are to build on last season's unexpected preliminary final appearance.

The wealth of talent at Arden St was barely tested in 2007, with 16 players figuring in 20 or more of the club's 25 games.

Season-long knee victim Nathan Thompson was the club's highest-profile absentee, while defender Josh Gibson, who missed 11 games after injuring his head in a fall at home, was the Roos' only other long-term casualty.

But Simpson believes his side is better prepared for an unluckier run with form and injuries in 2008, with the club's youngsters training hard over summer.

"We took in a huge group of really young blokes in last year's (2006) draft and this pre-season I've noticed those guys have really come on from where they were at the start of last year," Simpson exclusively told kangaroos.com.au.

"Guys like Lachie Hansen, Benny Warren, Benny Ross and Gavin Urquhart; they all seem to have really kicked on from last year.

"And that's really what you need as some of us senior blokes get a little bit older. We need that next group putting pressure on everyone for a spot in the side.

"I reckon we've got a really good starting 22 but we need to have a solid 25 or 26 if we're going to take the next step."

Simpson has also been buoyed by the sight of the club's latest batch of draftees and rookies, with seven of the Roos' nine newcomers for 2008 standing at 190cm or above.

What struck Simpson, however, was the fact that so many of these AFL rookies appear physically capable of playing senior AFL football as early as 2008.

"This year's draftees are a lot more physically mature than last year," Simpson said.

"There's a couple of 21 or 22-year-olds but even the younger ones, like Rob Tarrant and Levi Greenwood, have a bit of size about them.

"They all look like they've got strong bodies so if they can get a kick in the VFL, we'll be confident they can come up to AFL level and at least be physically capable of standing up for us."

As much as he believes this exciting crop of youngsters can play a role for the Roos in 2008, Simpson says success in 2008 will largely hinge on how well the club's emerging stars back up after what were breakout seasons for many of them.

Little was known of players like Hamish McIntosh, Jess Smith, Aaron Edwards and Josh Gibson heading into 2007, but all stood up to be key contributors in the Kangaroos' run to a top-four finish.

Even as a senior player who has seen and done it all over a 14-year AFL career, Simpson admits there is little he can do to make sure his young teammates repeat or improve on their efforts from 2007.

"There's not much you can do other than let them know that after you have a good year, like Hamish, for example, that he should really strive to take another couple of steps.

"You can keep an eye on how much they push themselves at training and what they do off the field but, you know, I'm not sure there's too much to be worried about with a lot of these guys.

"In many ways – and I'm sure the club wishes it wasn't like this – because of our low profile, I don't think any of our guys get ahead of themselves. I don't think any of them think they are better than they are.

"At the moment I reckon the guys like Hamish and Jess and all of the other boys who put their hands up last year will just evolve and even if they do have a flat spot, well, the good players usually work their way through those anyway."