Sandilands missed the first 14 rounds of the year after hamstring surgery in the pre-season. He then missed round 17 due to the flu and round 22 after fracturing his cheekbone against Melbourne the previous week.
But the Dockers have won eight of the nine matches he's played, the only loss coming with a depleted line-up against St Kilda in the final round.
Sandilands had 31 and 33 hit outs respectively in the Dockers' two finals wins, helping Fremantle win the clearances decisively against Geelong and the Sydney Swans, who are the best clearance team in the AFL this season.
"He's been crucial," Fyfe said.
"Aaron has been back a couple of weeks now. Zac (Clarke) has really grown and we've got our full contingent back now."
Sandilands also took three pivotal contested marks against the Swans in the second term and Fyfe believes Clarke's development has allowed the three-time All Australian to push forward to good effect.
"I think Zac's really grown with him out of the side," Fyfe said.
"But having him back now gives Zac the opportunity to go forward and Aaron an opportunity to go forward so he's really valuable."
Sandilands was loath to talk about his own influence but he was quick to praise Clarke's development in his absence this year.
"It's been huge progress for Zac," Sandilands said.
"He sort of took that No.1 role there - seeing all the injuries we had - and he's taken his game to another level.
"His pace and his aerobic capacity and his athleticism put him in really good stead and I think he has learned a fair bit over the last couple of years on where to position and what to do and he's become a really good player for us.
"I think the combination between the two of us is working really well and hopefully we can help the side out on the weekend."
Hawthorn is the best centre clearance team in the AFL and much of Sam Mitchell's 10 first-possessions in the preliminary final came from the supply of Hawks ruckmen Max Bailey, David Hale and relief ruck Jarryd Roughead.
The Grand Final battle between the big men in the centre will be pivotal to the outcome.
"They are a great combination," Sandilands said of his Hawthorn counterparts.
"Bailey and Hale together have played some great footy this year and Roughead can go in there as well, so it's a really solid combination and its going to be a really good challenge for Zac and I."