West Coast midfielder Xavier O'Neil will join an onball group that coach Adam Simpson hopes can find another level against Gold Coast to cover the absence of star pair Luke Shuey and Elliot Yeo.

The coach has stopped short of guaranteeing recruit Alex Witherden selection for Sunday's clash at Optus Stadium, however, as the former Brisbane defender finds his way in a new team.

O'Neill has played five games in two seasons and will join Tim Kelly, Dom Sheed, Andrew Gaff and Jack Redden as a front-line midfielder against the Suns after an impressive pre-season.  

Simpson compared Shuey and Yeo, who have shared four of the past five John Worsfold medals, to Geelong's champion pair Patrick Dangerfield and Joel Selwood, but said he hoped West Coast had the depth to cover them and compete.

"Those mids need to step up, absolutely," the coach said, declaring Kelly was fit to start his second season at West Coast after a thumb injury and Sheed had recovered from a knee knock. 

"Yeo and Shuey are like Dangerfield and Selwood for us, so they're pretty important players and hard to replace.

"But we think we've got enough depth. (Liam) Duggan is playing in the midfield now, and Xavier O'Neill.

"We're pretty happy with his development the last couple of years and we think he's in a pretty good space and ready to go."

Simpson said the Eagles were reasonably settled at the selection table and would now work out how they select the medical substitute after its late implementation this week.

Witherden and fellow recruit Zac Langdon, who has recovered from concussion and trained this week, were not guaranteed selection to face the Suns.

"He (Witherden) is a new player, the same with Zac. So they're still working our system," the coach said.

"It's been a very short pre-season for them to try and adapt. Zac missed a critical game for him and his development as well.

"They're long-term prospects for us. They're both early 20s. They might play, they might not. We're working through that today."

The Eagles and Suns will have the opportunity to watch a large portion of the opening round before their clash on Sunday and observe how AFL teams are adjusting to the stand on the mark rule and reduced interchange.

Simpson watched Thursday night's season opener as both Richmond and Carlton utilised their medical substitute, which the coach believed would be a positive for the League.

"It is a bit more work to prepare for and carry out. But done in the right way I think it will be a good thing," Simpson said.  

"I think on average there's one [injury] a game over the years, or just under one, where there's an injury and the player can't finish the game.

"Whether they play the next week or not I'm not sure (but) I dare say most games there will be a substitute used."

Meanwhile, Simpson said ruckman Bailey Williams was a week away from returning after injuring his ankle in a basketball accident.  

He said the Eagles intended to use different ruck combinations this season to support Nic Naitanui, with Nathan Vardy, Oscar Allen and Williams all providing different strengths.