The Power entered round 13 two wins clear on top of the ladder, but lost seven of their last 11 home and away games to finish fifth.
It was a form slump that had many questioning whether Port had peaked too soon, and after missing out on a double chance, most expected a quick ellimination once finals arrived.
The last two weeks have proved anything but, as the Power massacred Richmond before causing a huge upset last weekend against Fremantle in Perth.
Now preparing to take on Hawthorn in Saturday's preliminary final, Hartlett said the turnaround was due to the side refocusing on its training.
He said that as the losses began to mount the playing group took stock.
"The last couple of months we, as a whole group, really wanted to emphasise what we were doing on the training track, making sure we were getting the most out of our sessions," Hartlett said.
"Some teams have a tendency of falling away; we really wanted to ramp up our training and try and gain an advantage over the opposition.
"[Mid-year] was a really difficult part of the season for everyone and we had a couple of injuries and guys weren't in great form and there was a few things adding up.
"It was probably then that we thought, 'We really need to ramp things up', and try and gain an edge on the rest of the competition.
"[We're] probably only now starting to reap the benefit from that."
Hartlett said he expected to play a significant role in shutting down Hawthorn's powerful forward line.
Even without the services of Lance Franklin this season, the Hawks have three players who have booted more than 50 goals each.
Jarryd Roughead has kicked 64, while Jack Gunston and Luke Breust have both kicked 54.
Hartlett will be playing through the Power's midfield on Saturday, but said that' was where Hawthorn needed to be halted if its forwards were to be kept quiet.
"As a group we need to defend all over the ground; our midfielders and forwards need to apply a huge amount of pressure on the ball going inside 50 to make it easier for our defenders," he said.
"Hawthorn's forward line - Breust and Gunston and Roughead – these guys have all kicked 50-plus goals for the year and are all in pretty good form.
"We need to do our part further up the ground to allow our defenders to defend a bit easier."
Twitter: @AFL_Harry
