Former Port Adelaide midfielder Kane Cornes believes the Crows should throw the book at Collingwood ruckman Brodie Grundy in a bid to strengthen their ruck department.

Adelaide big man Sam Jacobs missed his side's loss to Geelong on Thursday night, with the Crows playing inexperienced ruckman Reilly O'Brien against Rhys Stanley, who's started the season in strong form.

Jacobs is entering the twilight of his career given he turns 31 next Wednesday, and Cornes believes Grundy should be the Crows' target this trade period.

“We know there have been reports of Adelaide being into Brodie Grundy from Collingwood - the South Australian, he’s got one year left on his contract before he becomes a free agent," added Cornes.

“(Adelaide) need to up the ante with that. It’s probably going to cost them $1.1 million to try and get him back (to South Australia).

“They need to do it, because they don’t really have any other option.

“You wonder whether they missed a trick not being in the hunt for Scott Lycett like Port Adelaide were. They’ve got some big issues with their ruck department.”

Cornes believes the Jacobs-O'Brien combo is Adelaide's weak spot, suggesting neither ruckman will have a big impact for the Crows over the coming years.

“It’s a massive issue for them. We know Jacobs’ best footy is past him at 31 years of age, and his formline would suggest that," Cornes added.

“They’ve got to somehow get him back in the side quickly, because from what I’ve seen Reilly O’Brien is not up to AFL level.”

The Crows have started the season with two consecutive home losses at Adelaide Oval, and own a 1-2 record after three rounds.