The Power have tumbled from first to fifth in the space of five games, with their only win in that period coming against Melbourne at Adelaide Oval.
On Sunday they were out-muscled by Collingwood at the MCG, falling short in all the physical indicators – contested ball (136-126), tackles (72-66) and clearances (35-33).
Hartlett, who was outstanding for the Power, said the team knew it was well short of the top four teams.
"If we keep going the way we're going we'll be lucky to make the eight," he told AFL.com.au.
"We need to have a good hard look at ourselves and get back to playing man's footy instead of little boy's footy and things will turn around.
"We coughed the ball up far too much on the inside of the contest and that put a fair bit of pressure on us.
"We'll need to toughen up a little bit I think between the ears."
Hartlett was Port Adelaide's best player, finishing with 23 possessions and eight tackles to go with his four goals.
When the Power were at their best in the third quarter it was Hartlett leading the way, kicking a brilliant 55m goal on the run and snapping another out of congestion minutes later.
Too many Port players slipped out of the game when it was on the line, however, and coach Ken Hinkley didn't mince words when addressing his team post-game.
"He went through us all individually and gave us a fair assessment of how we went," Hartlett said.
"He basically said, 'We don't look like we deserve to be playing finals footy at the moment'."
Hartlett said he was absolutely confident the Power could turn their form around and regain the confidence they were playing with in the first half of the season.
He said there was no bigger challenge for the players than facing the Sydney Swans next Saturday night at Adelaide Oval.
"We've got a six-day break so we need to make sure physically we're ready to go," he said.
"We know what to expect from Sydney; they're just going to play hard, contested footy … we need to get our heads around that challenge.
"We showed we were capable in the first 11-12 games of the season and personnel basically hasn't changed since then.
"We just need to find a little bit of confidence from somewhere and get back to the basics that were winning us games earlier on this season."
