Rasmussen said she and her mid-court buddies are pleased to provide some stability to the group.
"It only just dawned on us at training the other morning that 'hey, we're all still here'," she said.
"I think it is one of our strengths and it's just making sure we continue to build on it."
There was a time when Rasmussen's place in the team was looking a little shaky, after the influential wing attack absorbed setback after setback this season.
A niggly calf injury ruled out Rasmussen for more than half the Magic's season this year - a major blow for the athlete and her team.
But the four-week break between the end of the Magic's season and Silver Ferns trials gave her the opportunity to properly shake off her injury concerns and be ready to contest for a place in Southby's first test line-up.
"There's some great competition for places in the midcourt at the moment, so I was a little bit nervous coming into trials, but it was good to be in a position to know that I was able to give it 100 per cent and whatever happened after that would happen."
Southby said the midcourt posed the most difficulty for the national selectors, with the incumbents facing strong competition from the likes of the Steel's Gina Crampton and young Magic duo Sam Sinclair and Jamie-Lee Price.
What the Ferns coach hopes to develop in the next 18 months is similar selection conundrums in the other two areas of the court.
"Where we are at with the midcourt at the moment with some real quality players missing out, that's what we need at both ends of the court as well," said Southby.
"I'd like to think a year out from Commonwealth Games, we will be really settled in our combinations, with strong back-up options if injury and illness become a factor."
The three tests in the next week will be the first steps in helping build that depth, with Wednesday's match against South Africa in particular providing a strong opportunity to blood some lesser experienced players.
Building depth is also a key objective for English coach Tracey Neville, who has made sweeping changes to her line-up since last year's World Cup. Neville has brought out several budding young stars involved with England Netball's new full-time programme, which has been implemented with an eye on delivering success at the 2019 World Cup in Liverpool.
"What we're trying to drive is an over-supply of talent in the national squad," said Neville.
• A calf injury has put Anna Harrison's Silver Ferns comeback on hold.
The star defender has been ruled out of tomorrow's test against England, after picking up a calf strain in training this week. The Ferns management will make an announcement on Harrison's replacement today.
Harrison, who has not played for the Ferns since their disappointing Commonwealth Games campaign, earned reselection in the national line-up this month after taking time out for the birth of her second child.