MATT de Boer believes support for Fremantle ahead of Saturday night's preliminary final is so strong that the Dockers are converting West Coast fans for the week.

The Dockers were once viewed as the little brothers in Perth but on the eve of their first-ever home preliminary final, Western Australia has been enveloped by Fremantle fever.

"It's great for our fans and supporters, everyone's getting on board," de Boer said.

"I think we're even converting a few of the Eagles supporters over as well.

"It's good for WA football."

Asked if he supported Fremantle growing up in Perth, de Boer declined to comment suggesting he too may be a converted Eagle.

But de Boer is now a proud Docker and will play his 100^th game in the preliminary final against the Swans after starting life at Fremantle on the rookie list.

"It's memorable, and probably something I'll look back on when it's all said and done and be proud of," De Boer said.

Since Ross Lyon took over at Fremantle after the 2011 season, de Boer's improvement has been significant.

He averages four more disposals per game under Lyon than he did in three seasons under Mark Harvey. He's also kicked 25 goals in the past two years compared to 14 in his previous three.

His tackling has also become a major feature of his game. De Boer has laid more than 10 tackles in five separate matches over his career and only Sydney Swan Ryan O'Keefe and Brisbane Lion Jack Redden have laid more tackles in the AFL in the past two seasons.

"It's just great to be able to play so many games, firstly under ‘Harvs’ who gave me an opportunity which I'm very grateful for, and now under Ross, I'm learning a lot more about the game," de Boer said.

"I probably just understanding my role in the team a bit more specifically and where that fits in and how I can complement the side as well.

"That's evolution. You're going to get better and a bit wiser as you go along and I'm learning things too as I go."

De Boer will have an important role in the preliminary final against the Swans playing as either a defensive forward or a second run-with midfielder alongside Ryan Crowley as he did in the round eight draw at the SCG.

"I played on a few different players that night," de Boer said.

"I played up forward and in the midfield. I was on (Jarrad) McVeigh at certain points and definitely learned a lot off him and hopefully I can use that knowledge going into this game."