Eddie O'Sullivan feels Ireland need to move back towards a less attritional style of play "sooner rather than later".
Andy Farrell's side got off to a winning start in the Six Nations with a 19-12 victory over Scotland on Saturday but found the visitors difficult to handle physically at times.
Speaking on RTÉ 2's Against The Head on Monday night, former Ireland head coach O'Sullivan emphasised his belief that a change of approach is necessary in the long-term.
"I think we've got to think about this team moving away from taking teams on in attritional fashion," he said.
"That was what killed us in the World Cup when you think about it.
"We're not a team, I don't believe, that can go around bullying people.
"There are very few teams in world rugby that we can bully."
He pointed to the difference between the last year and when Ireland were at a relative peak in 2018.
"We were much smarter about how we went about our business," O'Sullivan said of that grand slam year when the All Blacks were also beaten in Dublin.
"Our ruck ball was much quicker and we put a lot of emphasis on the breakdown and were very precise at the breakdown. But we moved the ball as well a lot more.
"Jacob Stockdale was scoring tries for fun in 2018. He didn't get half the chances last year because we changed the way we played.
"We need to move back in that direction sooner rather than later."
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O'Sullivan added that he "expected a better performance than we got" against Scotland.
"It's got to be an incremental step forward next week," he said of Saturday's upcoming round-two fixture against Wales.
"Because had it have been Wales rather than Scotland last Saturday, we probably would have lost.
"Scotland are not as good as we made them out to be or made them look.
"So there is plenty to worry about but plenty to work on."