Neil Back thinks England captain Chris Robshaw is not good enough to be considered among the top five opensides in the world and also has concerns over the focus of James Haskell.
Robshaw will lead the tournament hosts throughout this autumn's World Cup and resumes his role as skipper for Saturday's warm-up match against France in Paris after being rested for the 19-14 victory over the same foes last weekend.
Back is one of Robshaw's most celebrated predecessors in England's number seven jersey, winning 71 caps in an 11-year Test career that peaked when lifting the Webb Ellis Cup in 2003.
While the World Cup winner rates Robshaw, he insists there are areas of his game that leave him trailing his openside rivals from other nations.
"Chris has improved and is a very good player, but he's probably not in the top five opensides in the world," Back, who was speaking at the SSE #soundsofvictory pop-up shop in London, told Press Association Sport.
"If you were putting together a world XV, he wouldn't be under consideration.
"As a seven I'd like him to develop his offloading game so that he's not taking the ball into contact so often.
"Robshaw's a good ball carrier, but he takes it into contact too much and that doesn't help the continuity of the team.
"He's improved over the ball, but if you're talking about the world's best players in that regard then he wouldn't be in the conversation.
"But he has grown as a captain, becoming more assured and confident. His support lines have improved, as has his foot speed away from contact, rucks and the set piece."
Back also has misgivings over Haskell, England's blindside flanker at the Stade de France and a certainty to be one of the five back rows selected for the World Cup squad.
Haskell has set-up a health and fitness business complete with website, YouTube videos and a supplement range and recently appeared in Hello magazine alongside celebrity girlfriend Chloe Madeley.
"Haskell has really come into his own this year, although I'd personally wish he'd concentrate on what he does on the field more than what he does off it," Back said.
"It's just an impression I get and it may take away from his performance, even if it's just a little bit.
"To be the best you must have balance in your life, but particularly in a World Cup year you must have full focus on being the best you can possibly be for England.
"When he maximises his potential there, then everything off the field will come. He may say he's got the balance right and time will tell.
"If he contributes to a successful World Cup with England, then he can say he got the balance right.
"Over the ball he's very strong and he usually wins in the contact area. He's also good at getting turnovers."
Meanwhile, Joe Launchbury is reunited with Courtney Lawes as England field their first choice second row pairing for the second of their three World Cup warm-up matches.
Launchbury made his most recent Test appearance on the 2014 summer tour to New Zealand after a neck nerve injury left him spending the majority of last season in the treatment room.
"It's been a long road back into international rugby but I was always confident that I would get back here if I worked hard," Launchbury said.
"You don't realise how special playing for England is until it's taken away from you. Watching guys train, prepare and play is frustrating because you realise it's everything you want to do.
"When I came back for Wasps at the end of last season, the neck felt good and strong. I always knew it would do, but it's good to prove it.
"I haven't had any issues with my neck since and I've trained fully all summer. I feel like a completely fit player, which is great."