ERIC Mackenzie needs to rebuild some confidence as he continues to work his way back to his best football following a knee reconstruction, West Coast coach Adam Simpson says.

Mackenzie played the first 11 matches of the season for Eagles after missing all of last year following a knee reconstruction.

The Eagles' 2014 best and fairest missed the loss to Adelaide in round 12 with a virus, but was not immediately recalled in round 13 and instead played for East Perth in the WAFL.

It was his first game at WAFL level since 2011, but his omission was overshadowed by the Eagles' decision to drop ruckman Scott Lycett for disciplinary issues for the clash with the Brisbane Lions.

Simpson said Mackenzie has been battling to adjust to the Eagles' new defensive structures in the first half of the year.

"He's just struggling for a bit of form at the moment," Simpson said.

"Coming off his knee and trying to adapt to the way we play and where the game is at the moment, it's changed a bit since 2014. So we're trying to get him some form. At the moment he's doing that at East Perth."

Mackenzie trained with the senior group on Wednesday ahead of Thursday night's game against Essendon, but Simpson did not confirm whether he would be recalled prior to the session. 

Mackenzie played his best football in 2014 as a lock-down one-on-one key defender, making the All Australian 40-man squad and claiming the Eagles' club champion award. But his knee injury in the 2015 pre-season forced the Eagles to shift to a zone defence, which became a key component of their run to the Grand Final.

While Mackenzie has been trying to adjust to the new system, Simpson said the 28-year-old needed to find "some touch".

"It's coming back from a knee reconstruction and having confidence in your body," Simpson said.

"I think that's the thing that everyone works through in their first year back, and not many players just come back in and go straight back into it. Not key position players. We've got to give him a bit of patience."

Lycett will come straight back into the side to face Essendon on Thursday night after serving his penance in the WAFL, with Simpson saying he was pleased with the ruckman's response.

"He's available this week so he'll come back in," Simpson said.

"He performed really well at East Perth. He understands how he disappointed the club and himself and the players. He's got some work to do to get their trust back, but he's made the right steps."

Lycett gets an opportunity to be the number one ruckman in the absence of injured star Nic Naitanui. Jonathan Giles and Fraser McInnes, who shared the ruck load against the Lions, trained with the Eagles' development group on Wednesday, as did midfielder Jack Redden.