WEST Coast ruckman Callum Sinclair has credited Eagles' ruck coach and club games record-holder Dean Cox with helping fast-track his development.

Sinclair has established himself in the Eagles line-up over the past five weeks after starting the season as a third-choice ruckman behind Nic Naitanui and Scott Lycett.

The 25-year-old was even trialled as a key defender at WAFL level as the Eagles searched for options after the season-ending knee injuries to Eric Mackenzie and Mitch Brown.

But a dip in form from Lycett gave Sinclair a chance to partner Naitanui in the ruck in round five against Greater Western Sydney. Since then he's averaged 19 hit-outs, 13 disposals, five marks and has kicked four goals in the last five weeks.

Sinclair, who is 200cm and 99kg, told AFL.com.au he had worked hard with Cox on body positioning given his slightly lighter frame compared to most ruckman in league.

"It's been a big emphasis on body-work, body technique, things like that," Sinclair said.

"When you're coming up against guys who are 110kg every week, it's not the easiest job.

"But with (Cox's) level of experience he knows the game inside-out, particularly as a ruckman, so I just try and draw as much knowledge as I can from him."

Cox told AFL.com.au that body positioning against larger opponents is the biggest challenge Sinclair will face.

"He's got to use his brain as much as he possibly can and try a number of techniques," Cox said.

"If one is working, keep going with that. But he's got a second, third or fourth technique to go to and try and mix it up and show a lot of variety at stoppages.

"That's the challenge, and because he's such a great student and really enjoys analysing, it helps him out in that area as well."

Sinclair said Eagles coach Adam Simpson had kept the message pretty simple since he's come into the side.

"(I've) just got to be ultra-competitive, bring the ball to ground when I can and have that versatility of trying to go forward and also play as a ruckman as well," Sinclair said.

"He wants the whole group to be pretty versatile and play a variety of positions considering the amount of injuries we've got."

Sinclair's is a great story of persistence. Originally from Victoria, he was overlooked in the 2010 draft and then endured knee problems in 2011.

He left Port Melbourne and moved to Perth to play with Subiaco in the WAFL. After a dominant season that included a call-up to the WA state side, Sinclair was recruited by West Coast as a mature-age rookie. He played five games in 2013 and was upgraded to the senior list in 2014. He battled for opportunities last year playing just four games, but pressed his case in the WAFL during the early part of this season. 

Sinclair is happy with the way the combination is working with Naitanui, but is not getting ahead of himself as Lycett continues to push his case in the WAFL.

"The combination is going really, really well," Sinclair said.

"Obviously happy with getting a good base level of consistency throughout the last month. It's only early though, so it can come undone pretty quick."