Victor Matfield predicts that Jordie Barrett's move to Leinster will separate the Blues further from the chasing pack.
The Blues last won the URC title in 2021 and it is six years since they last lifted the Champions Cup trophy. However Leo Cullen's side are pushing hard for silverware on the double at the business end of this season.
Former Springboks star Matfield has been impressed by the Blues' signing of his compatriot Jacques Nienaber as senior coach - and, on the playing side, by Joe McCarthy's breakthrough season.
READ MORE: Leinster sign ex-Munster star as their new attack coach
With top All Blacks performer Barrett joining next December for seven months from the Hurricanes, Matfield feels that Leinster can push on to a new level.
"It's always great to bring a top player like that to your Union," the former Boks second row said. "It's just a different view on how things work, taking some things from that, bringing IP from the All Blacks to that squad.
"They've got this fantastic Ireland team that's won everything, the Leinster team that's almost unbeatable, and you've added Jacques Nienaber so you've brought something from the successful Springboks.
"And now you're bringing in Jordie Barrett, one of the stars of the All Blacks. It's just adding more IP into that whole system, so that should make it more difficult for other teams - and it will probably just take Leinster further ahead of everyone else."
Matfield admits he was "very surprised" by the level of performance produced by McCarthy in this year's Six Nations.
Selected by Andy Farrell for the opener in Marseille, McCarthy was outstanding for Ireland on the night and went on to start in all five matches as the title was retained.
"When they picked him ahead of some other experienced guys, I thought who is this guy, and he stepped up," said the World Cup winner.
"He had a really good Six Nations. He's a fantastic ball carrier, he's always in your face. When you have that one guy in your pack that you know everyone in the other pack looks at and thinks, 'ah, do I want to take him on or take a step back', then you're really on the front foot.
"That's what we always had with Bakkies Botha, it didn't matter where we went, we always knew the other guys were thinking that when he was arriving at the ruck.
"So he's very good for Ireland - it's going to be very interesting seeing him over here in South Africa (on the summer tour). He's going to be valuable to that Irish pack for a long time to come."
Matfield first worked with Nienaber with the Cats over 20 years ago, when the two-time World Cup winning coach was starting as a physio before becoming a fitness coach.
Premier Sports pundit Matfield, who was speaking on a media call for the BKT United Rugby Championship, describes Nienaber as "the best defence coach in the world" - with the added quality of knowing how to win semi-finals and finals.
"We've already seen last week, Leinster were just dominating (La Rochelle)," he said. "We'll see his full value in the semi-finals and finals - if Leinster wins both competitions, everyone will know why they brought Jacques over.
"The 46-year-old says the key to Nienaber's double World Cup winning success alongside Rassie Erasmus was preparation. "The two of them, they live, eat, sleep rugby," Matfield stressed.
"He's very confident in how he sees the game and what he believes in. When you get someone like that, even if it's a team that has been playing differently to what he's used to, he'll bring something that will definitely help them.
"The biggest thing about Jacques's defence is work-rate, it's getting off the ground and getting off the line.
"If you look at Leinster on attack, if they apply that to their defence - that same work-rate, getting into the shape, being an option, getting off the line and being accurate in what you do - they'll just get better."
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