Port Adelaide has lost four games, against top eight sides Hawthorn, Geelong, Sydney and Adelaide, by 15 points or less in 2008 and has been in winning positions in three of those four games.
Fremantle has also struggled to put together four-quarter efforts and have blown three-quarter-time leads in their past four matches.
Various remedies for both clubs' woes have been raised this week, but Primus said the ability to win was a simple matter of belief.
"When you don’t win a couple of those close games, or if you lose a three-quarter-time lead, it seems to perpetuate itself," he said. "That’s about the only reason for it. I don’t think you can throw in a fitness issue, it’s probably just an issue of belief.
"If Fremantle had a won a couple of those games, they’d actually believe they can overrun teams in the last quarter, that’s how close the margin is.
"You just need to win to get that belief back. You’ve got to keep looking at what you’re doing and practising all your good habits. You look at all the positives and negatives out of the game and just keep believing and keeping the group up.
"A win does fix most things and it does push the group in the right direction."
The Power had a jog and swim at Grange Beach on Friday morning, rounding out a lighter week.
On Monday, the players relaxed with a game of indoor cricket and had a team lunch and golf on Wednesday.
"This week we looked at other times when we’ve played Sydney and, obviously, going on to a road trip to Perth it’s all about freshening the group up," Primus said.
"We look at all the indicators as to how the players are feeling and we thought it was a week to really freshen them up and make sure when we get to Subi in Perth, that we’re ready to run."
Nathan Krakouer and Paul Stewart, both named in the 25-man squad, joined in Friday morning’s activities but forward Damon White was absent.
The Power will take 24 players to Perth on Friday afternoon with Krakouer expected to replace the injured Brett Ebert in the final 22.
"We’re going to meet as coaches now and go through the final selection," Primus said.
"Krak (Krakouer) will come over with us and we think he’s probably the best replacement for Ebo (Ebert). He played against West Coast over there a month ago and he’s a Perth boy, so we’re leaning that way."
Primus was expecting a physical approach from the Dockers, who have added hard nuts Josh Carr and Mark Johnson to their 25.
Twelfth on the AFL ladder with a win-loss record of 3-6, Primus said making the eight was still a realistic goal for the Power.
"We saw what we were able to achieve last year and the players want to be able to play finals again," he said.
"With the way the season is going, apart from the top two or three teams, every other spot is still gettable.
"Obviously, if we don’t win this week it makes it harder, but we still think we have the ability to string games together in the second half of the year and to make the eight.
"A loss this week would make it a lot more difficult, but it’s nowhere near impossible and nowhere near unachievable."
