Once Rieko Ioane unsuccessfully shot out of the line, you could already hear the chatter: Leinster’s defence has been exposed again.With multiple defenders in-field taken out of the game, Ioane had to choose between two pink and blue shirts. When he made his gamble, Matthieu Jalibert picked him off and Pablo Uberti scored in the corner. Ever since Jacques Nienaber arrived to overhaul Leinster’s defensive system, all eyes have been on its efficacy. Could it get them over the line on the big days? Three years into Leinster’s defensive experiment, this was its most porous big day out, Bordeaux’s tally of 41 eclipsing the 37 points scored by Northampton 12 months ago. While pictures of hapless shooters out of the line are difficult to forget, the blitz was not the issue on Saturday. It was instead another pillar of the Nienaber system that failed. One that should lead to difficult questions, albeit not solely for Leinster’s coach and his methods. Before the line speed, something else needs to happen to permit the shuddering man-and-ball hits desired by the blitz. Leinster players have spoken extensively of the “s**tfight” they want to bring to defensive collisions. Dominate tackles. Spoil rucks. “Barge” is another new favourite term. Union Bordeaux Begles’ Pablo Uberti scores his sides 2nd try of the match against Leinster. Photograph: James Crombie/Inpho In the first half on Saturday, Leinster had just one breakdown turnover. Even then, Josh van der Flier was made to work so hard to secure possession. [ Leinster blitzed by Bordeaux Bègles as they suffer deflating Champions Cup final defeatOpens in new window ]The French side’s attacking breakdown work was sensational. Carriers were never separated from support. Legal violence ensued at every ruck, clean-out men targeting with lethal precision the Leinster tacklers trying to stay on their feet to disrupt. Adam Coleman set the tone with a shuddering hit on Dan Sheehan before the hooker had even finished a tackle.“That’s something Leinster have been really good at, slowing down the ruck,” said Noel McNamara, Bordeaux’s attack coach. “I think the average ruck speed is over four seconds against them, I would imagine today was a little bit quicker and that was a big factor for us.”Figures for said ruck speed are not publicly available. What we do know is 63 per cent of Bordeaux’s rucks lasted fewer than three seconds. That backline is always going to do damage with quick ball. Especially when the outside blitz had minuscule time to ready itself. In the semi-final against Toulon, Caelan Doris received criticism for giving away penalties at the breakdown. On Saturday, he didn’t even get a chance to think about infringing. When asked why he and his team-mates struggled to slow the breakdown, Doris pointed to what happens earlier in the play. “I think it’s a step before that, it’s the contact area in the tackle,” explained the Leinster captain.“You’ve got to slow their ball down with proper tackle contest and we didn’t have that consistently enough in the first half.“A key component of that is the tackler area and there’s an individual responsibility there as players. I know I had a few, which weren’t good enough and I’m sure a few of us are feeling that way.”Union Bordeaux Bègles' Cameron Woki is tackled by Leinster's Andrew Porter and Tommy O'Brien. Photograph: Dan Sheridan/Inpho To Doris’ point, according to the Rugbypass database, Leinster made only one dominant tackle. Last time out against Toulon, they had eight. “They’ve also got a very strong carrying forward pack,” said Doris. “So, we got stuck in a bit of a negative loop of allowing them quick ball, quick ball, quick ball, and they’re away.”By failing at the defensive breakdown, Leinster couldn’t implement Nienaber’s line speed. In truth, little of their display was what we’ve come to expect of their senior coach’s calling card. Instead of kicking plenty, being content without the ball and efficient inside the 22, Leinster continued the Irish tradition of multiphase play – with the odd moment of fleeting success – into the heart of an all-consuming defence. Perhaps due to desperation to chase the game, Leinster made more carries than Bordeaux (162 v 104), kicked less (one kick for every 13 passes, compared to UBB’s ratio of 1:4) and were inefficient inside the 22 (1.5 points per entry to UBB’s 4.3). In defence, do Leinster have the cattle up front to deal with ferocious French clearouts? With an international-laden pack, the answer should be yes. Doris still believes in the system. “Absolutely. I think we’ve seen what it can do over the last number of seasons when it’s delivered on properly.” What, then, of the other side of the ball: does building a more possession-heavy attack expose a naivety on the important days? If Leinster are aiming to carry out Nienaber’s plans on one side of the ball, while reverting to type in attack, are they merging a coherent game plan or muddled between different ideologies?Until they win their long-awaited fifth star, most will point to the latter.[ Joey Carbery set for Leinster return, Ulster had eyes on the wrong prize: What we learned from the European finalsOpens in new window ]