Fremantle's failure to handle the occasion in 2021 and its inability to perform with its season on the line on Sunday should burn through the summer, according to coach Justin Longmuir.

Freo needed to beat St Kilda at Blunstone Arena to remain a chance for a top-eight finish, but they crumbled instead and suffered their fourth defeat this year by more than 50 points.

Their inability to finish the year on a high "should burn and it should burn for a while", Longmuir said, conceding Fremantle had been too inconsistent in 2021 and left too much to too few on Sunday.

"History would say when we've been in these positions with finals on the line or in the eight, we haven't handled it," the coach said.

"We haven't handled coming off the back of good wins, we haven't handled playing at new grounds. There's a lot of things we haven't handled this year and a lot of situations we need to dig a bit deeper into.

"We need to learn from then experience we've been through this year and become more consistent as a footy club, on and off the field. We've got a lot of work to do, but we knew that before today."

Longmuir said maturity was an issue for Fremantle, who again fielded the youngest team of the round as they ended the season with a mounting injury list, with ruckman Sean Darcy and forward Sam Switkowski each suffering hip injuries.

He said the Saints had got through his team far too easily from half-back and the Dockers' pressure had again been sub-standard.

With a sixth consecutive year out of finals confirmed, the coach said building towards sustained success needed to remain Freo's focus.

"Our members want to see us in the finals, but we need to make sure we have a longer-term view," Longmuir said.

"We need to continue to build a really deep list that will take us to sustained success, not just one year in finals."

Fremantle's list will again change, with outside run the club's priority in the off-season.

Longmuir said an answer from out-of-contract midfielder Adam Cerra on his future would be needed before the NAB AFL Trade Period.

St Kilda coach Brett Ratten also forecast change for his team after falling from sixth in 2020 to 10th this year.

He described the season as a missed opportunity after entering the mid-season break with a 5-8 record and sitting outside the top eight for every week except round one.

The club had learned about dealing with the expectations of being a finalist last year and how to embrace challenges.

"When you reflect back on successful years, it's about the growth of the year before when you've been challenged by adversity," he said.

"To think that we've not had the year we wanted but we still won 10 games of footy is positive."

Ratten said the Saints would need now "re-jig" their gameplan over the summer to compete with the AFL's best teams and target specific players.

"I think there will be a little bit of work done post-season in regards to recruiting and trading if there's something there, and we'll probably get some kids in as well," he said.

"We've targeted a few things outside our football club, a few players, but we'll wait and see."

Justin Longmuir post match Q&A v St Kilda
'We're all hurting' - Freo look for answers to inconsistency
JL update on Switkowski, Darcy, Pearce and Cerra