Bernard Jackman says Munster's coaching staff must "change old habits" and warned it could take until January before they start to show signs of serious improvement.
Graham Rowntree's reign as head coach got off to a losing start as a below-par Munster suffered a 20-13 defeat against Cardiff in their BKT United Rugby Championship opener.
Bernard Jackman says it will take time for Graham Rowntree and his coaching staff to turn things around at Munster
The visitors conceded two tries off first phase from set-pieces at the Arms Park while Max Llewellyn's opening try was the result of some abject defending.
Rowntree takes his side back to Wales on Sunday to face the Dragons, live on RTÉ2 and RTÉ Player, and Jackman said patience is required.
The former Ireland hooker told Against the Head: "Munster will be happy with a bonus point given the content of the game. To concede those two set-piece tries, that's an easy fix, and Denis Leamy will tighten up all those areas over the next month.
"From an attacking point of view, you can see at times what Mike Prendergast wants to do, but there was that lack of cohesion and clarity.
An early breakthrough for Cardiff as Max Llewellyn punches a hole through the Munster line.
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"You've got to change old habits. Johann [van Graan] and Rassie Erasmus before him had a very clear blueprint of how the game should be played. That's what they've been taught for the last six or seven years. You've got to retrain them. They're also missing some internationals.
"I think it'll be January before we see what Munster are really about under Rowntree, Prendergast and Leamy. They've had a very short pre-season but the initial impression, and from what I'm hearing from players, is it's a breath of fresh air. They like the way it's going."
Jackman said the opening-round defeat should not signal "panic stations" for Munster and added Cardiff offered a glimmer of hope to Welsh club rugby after years of underperformance.
"It's good for the league if Cardiff get back," said Jackman. "On paper they're the best Welsh team. Signing Taulupe Faletau, Liam Williams, Thomas Young - the league needs a strong Cardiff.
"Obviously we hope they don't be getting points every week against Irish provinces but there's a load of improvement left in Munster there."
'Leinster must rectify defensive lapses'
Jamie Heaslip, Donncha O'Callaghan and Murray Kinsella reflect on Leinster's victory over Zebre
Jackman doesn't expect a major post-mortem in Leinster either after their shaky start to the season in Italy, where Leo Cullen's side suffered a second-half collapse against Zebre but held on for a 33-29 bonus-point victory.
They face further Italian opposition on Friday when Benetton visit the RDS and Jackman believes that low-key start would have been factored into his former side's pre-season plans.
"Cullen and Stuart Lancaster know how to manage their squad," said Jackman. "They normally play over 55 players in the competition. They saw their first game was Zebre away and they got the five points that they probably targeted.
"Obviously Zebre got a bit closer than they would have liked. They only played one pre-season game against Harlequins because effectively thought they saw Zebre as one. Most players would normally play two and a half pre-season matches.
Zebre have made it a four-point game as Leinster concede a fifth try in Parma
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"The less pre-season games you play, the more time you can spend on strength and conditioning. If you can avoid them it can help you peak at the right time.
"Leinster had 21 players away with Ireland, they'll all be on individual schedules. They nearly got caught, but they didn't. They got five points and at the season they won't be saying they should have started a week earlier.
"Defensively it was a little bit unusual for them because no matter what players play for Leinster, they all seem to be on the same page. And you saw some examples of players ball-watching and man-watching. That's something they'll obviously have to rectify."
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Watch live coverage of Stormers v Connacht (24 September) and Dragons v Munster (25 September) on RTÉ2 and RTÉ Player.
