Alan Quinlan believes Ireland must not hit the "panic button" after their seventh quarter-final defeat in nine World Cups.
The former Munster and Ireland flanker has called on incoming head coach Andy Farrell to cut out the "predictability" that left Joe Schmidt's side hamstrung in 2019.
Ireland swept the board in a glittering 2018, claiming a Six Nations Grand Slam before beating back-to-back world champions New Zealand for the first time ever in Dublin in November.
Head coach Schmidt's team peaked with that stellar year however, slipping off the pace afterwards with the astute Kiwi's tenure ending with Saturday's 46-14 thumping by New Zealand in Tokyo.
Now defence coach Farrell will take the reins with former England centre Mike Catt joining the set-up, and Quinlan admitted Ireland have to reinvent their attacking game.
"I certainly wouldn't press the panic button and do something like move on seven or eight players," Quinlan told the PA news agency.
"But what I would try and do is bring in a number of young players. I'm sure Andy Farrell will do that.
"A week ago everyone was saying how badly Johnny Sexton was needed against Samoa, for example.
"But there does need to be new blood, new faces, and that can bring enthusiasm.
"We've heard the word predictability a lot in the last 12 months about how Ireland play.
"A lot of teams have given Ireland compliments that even if you work out their game plan they are so efficient that you can't stop them.
"But the game has moved on, and it's moving on again, to having more variety in breaking down defences.
"Ireland have been stopped a lot in the last 12 months, so they have to start doing things differently and making it difficult for opponents to analyse them.
"Ireland have decent strike runners and they probably don't get enough of the ball.
"We saw a master class from New Zealand in how to get the ball to your strike runners really quickly.
"And it's not about them scoring tries off that but it's the line breaks they make.
"It's actually setting them up one-on-one in a bit of space, and that in turn creates quick ball.
"It's very disappointing and it's tough on them, but they should be criticised because they under-performed."
Taskmaster boss Schmidt built Ireland into a formidable machine that at its best was difficult to disrupt, but latterly opponents found ways to throw a spanner into the works.
Ireland turned their 2018 Grand Slam into a frustrating third-place finish at this year's Six Nations, losing 32-20 at home to England and then 25-7 to Wales in Cardiff.
Schmidt's men then suffered a record 57-15 loss to England at Twickenham in August, before slipping up 19-12 to hosts Japan during their Pool A campaign.
A comfortable 27-3 win over Scotland perhaps masked some shortcomings when viewed in hindsight, and Quinlan now believes Schmidt has suffered for not finding a solution to Ireland's attacking deficiencies.
"This defeat does taint Joe Schmidt's legacy a little bit because it's the World Cup, but I don't think it should," said Quinlan, speaking as an ITV pundit.
"Unfortunately it's another four-year wait to try to go past that quarter-final.
"And it's the tag around Irish players' necks.
"I don't think they ever healed from the Six Nations, then losing at Twickenham and to Japan damaged confidence.
"Not many teams would have been able to cope with the tempo and pace, the execution and accuracy and pace that New Zealand produced. They found an A-plus performance.
"Ireland lacked shape in attack and couldn't influence the game in any way.
"It's a build-up of nine months of hitting a brick wall and not being able to figure it out.
"And that's hard on Joe Schmidt, because he has to take responsibility."
