Ruaidhri O'Connor: Scottish inquest puts focus on Andy Farrell and his defence
Over the course of the first 27 games of the Joe Schmidt era, when Les Kiss was the defence coach, Ireland conceded an average of 15 points a game. In the five games of last year's Six Nations, when Schmidt took charge of the rear-guard, it increased to 17 points per game. In the eight matches since Andy Farrell began his stint as defence coach the tally has risen to 24.
The Lions defence guru has presided over a difficult run of fixtures, facing South Africa away three times, New Zealand twice, Australia, Scotland and Canada.
Over those eight matches, his team have shipped 23 tries, an average of 2.8 per game, and the manner in which Ireland's wide defence struggled at Murrayfield last Saturday as they opened their Six Nations campaign with a defeat to Scotland has caused major concern.
That rate of concession forces Ireland to score plenty of points if they're to win games and when their lineout creaked and their attacking accuracy was off against Scotland last Saturday they paid the price.
Before the tournament began, Schmidt was positive about the direction his defence was moving in.
"Andy Farrell, since he's come in, has done a wonderful job," he said at the Six Nations launch.
"He's had less time to influence the group and he's still building that defensive system and the priority for every player in that system.
"We've done some fantastic defensive stuff. There are some players who are further ahead and who have a better understanding.
"You always want everyone to have the same understanding so everyone is up to speed. You'll always hit the odd speed bump, so it shows we've made real progress."
So, was Saturday a speed bump or an eye-opener as to how teams can get at Ireland for the remainder of the performance?
Certainly the feedback coming out of Ireland's camp this week is that Saturday's issues were largely down to an attitude issue at Murrayfield.
They reckon that their second-half defensive performance - when they made plays and restricted the Scots to two, admittedly crucial, penalties in 40 minutes - shows that when they have their mindset right there's nothing wrong with their defence.
But there remains concern about their vulnerability out wide when their opponents win the collisions in tight, something Farrell was presumably tasked with addressing given the manner of Ireland's exit from the World Cup at the hands of Argentina.
The first 40 minutes saw the Scottish back-three get big gains off limited possession, as Finn Russell tried to move the ball wide whenever he got the chance. Scotland's attacking shape was designed to use the full width of the pitch and whether it was by dint of communication issues or a focus on defending around the ruck, the ball never got wide.
Read more: Kelly blow ahead of U-20s' Italy clash
"It was more our spacing around the ruck," Robbie Henshaw said yesterday.
"We were too narrow and weren't getting off the line. We were square on them instead of hunting them from the inside. Our spacing was what we needed to fix. They didn't have the quickest of ball for us to adjust our spacing to the right measure.
"In the second-half we did fix it and that allowed myself and Garry (Ringrose) get off the line, putting in some shots and shutting down Finn Russell."
Getting off the line is the key.
Farrell's model is predicated on aggressive line-speed, but if Ireland are resetting because Vern Cotter's ball-carriers are getting over the gain-line, it is difficult to get up in their faces from a position of retreat.
The idea is to force the opposition into pressurised decisions and hope to make big plays or force errors. Unfortunately, when the line is sluggish the ball gets wide and tries are inevitable.
The loss of vocal, experienced and hard-hitting defenders like Johnny Sexton and Jared Payne only adds to the issue. Peter O'Mahony is another key communicator. Of the five players who were so missed against Argentina at the World Cup, only Sean O'Brien played on Saturday.
For the first six games of Farrell's reign, the defence on the edges wasn't much of a problem. South Africa did get around them at times, but Ireland managed to scramble. New Zealand went through them and before Australia came to Dublin only Canada had managed to get some penetration out wide.
Australia, however, had lots of joy out wide and perhaps the euphoria that greeted the manner of that win - and the fact that two of the backline for the entire second-half was unrecognisable from the one that started - saw the issues largely ignored.
Former Ireland coach Eddie O'Sullivan was concerned.
"I think it's overrated, to be honest," he said of Ireland's defence under Farrell on 'Off the Ball' in November.
"The big take from our defence during the autumn has been (that) our discipline has been extraordinary.
"The idea we have conceded a grand total of 11 penalties in three matches, and the opposition have conceded 41, is phenomenal. But our defence per se is not particularly good... our tackle rate is just barely over 80pc over the three matches, that's really worrying. Plus the fact teams are scoring in excess of three tries a match.
"We're measuring ourselves against Australia and New Zealand, but they're scoring in excess of three tries a match against us, with 40pc possession and 40pc territory.
"What if we go into the Six Nations and teams get 50pc possession and 50pc territory and they don't give up 15 penalties. So they've a lot more ball, a lot more territory. And how do we score two to three tries a game with less possession and less territory?
"We're still making poor decisions defensively at times. We're not making poor decisions in terms of discipline, we're incredibly disciplined. And that's fantastic. If you know you're no t going to give up five or six penalties a game that's a huge advantage.
"But if you look at (Tevita) Kuridrani's try, it's a schoolboy error. We had five defenders on the left-hand side of the ruck against two Australian attackers and they had a walk-in...that's pretty poor.
"We're leaking tries against teams with 40pc possession. I don't think that's great defence by any metric."
Although his last job with England ended in disaster, with his defence ripped apart by Australia at the World Cup, Farrell arrived into the Irish job with rave reviews from current and former players like Paul O'Connell, Brian O'Driscoll and Conor Murray.
They all spoke highly of his passion for defence and eye for technical detail, while Warren Gatland thought highly enough of him to reinstate him as the Lions defence coach again.
His influence has been hailed as part of the general improvement during the second-half of 2016 and reports from behind the scenes are positive.
For all of that, Ireland are conceding too many tries. It's up to Farrell to find a solution.