Regarded as Brisbane's greatest centre, Renouf believes using Benji out of position will have no benefit for the club.
“It (signing Marshall) is a deadset joke. I honestly don’t know what Wayne is doing there,” Renouf told The Courier Mail.
“I can’t understand Wayne’s decisions and where the club is going.
“Benji is a six (five-eighth) or seven (halfback) and Wayne is talking about playing him as a centre. I don’t see any benefit to playing Benji Marshall at centre.
“If you are coming up against an opponent with speed, they can burn you on the outside and I can’t see Benji shutting down younger, faster players.
''Centre is one of the hardest positions to defend in and I don’t see what Benji can offer there.”
The 46-year-old also had concerns with the forward pack after veteran Corey Parker's departure.
“We are really going to miss Corey Parker,” Renouf said.
“I’d be interested to know Brisbane’s plan to replace him.
“Even Wayne letting go of Jarrod Wallace to the Gold Coast ... he was playing some great football for them off the bench.
“They are going to miss Corey big time, just his leadership and his workrate.
“There is a big hole in the Broncos’ pack. They need an aggressor in their pack. They should chase someone like (Roosters prop) Dylan Napa.”
The Broncos have lost centre Jack Reed and veteran Corey Parker to retirement and are yet to find suitable replacements.