Lancaster becomes Cullen's No 2 and a half
The position of 'senior coach' didn't exist in Irish rugby until yesterday morning and then along came Stuart Lancaster.
The appointment of the former England head coach has altered the power dynamic at Leinster's UCD base, even if the current hierarchy still shows Leo Cullen at the top of the tree.
Leinster are keen to sustain the image of their former captain as the top man, but the appointment of a far more high-profile coach as his No 2-and-a-half has muddied the waters.
For all that he has a reputation to rebuild after steering England out of their home World Cup at the pool stage, the Cumbrian is a vastly more experienced operator than his new boss.
He will replace Kurt McQuilkin in the Leinster set-up, filling the boots of the popular defence coach who has had to return to New Zealand.
Lancaster will have responsibility for the defence at the RDS, but he is not their defence coach. He will also have input in the attacking side of the game as well and also hopes to involve himself in Peter Smyth's academy.
All of which makes sense for a man whose experience since leaving his job as a teacher has been a combination of senior head coaching and elite player development.
It just sounds more like the job that elsewhere is known as a director of rugby.
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However, at his introductory press conference yesterday, Lancaster said he was happy to let Cullen make the difficult calls and face the media on a regular basis, but one wonders how long it will take before he will want to make his own decisions.
His contract runs until the end of the season, along with Cullen's, and the province have some big decisions to make between now and then.
Part of the reason they have found themselves with this strange scenario was their impulsive decision to sack Matt O'Connor in 2015 without having a succession plan in place.
That pitched the then forwards coach Cullen into the top job before his time and, like Anthony Foley in Munster, he has struggled with the task.
Last season fell well below the standards Cullen helped create as captain and now he is under pressure to deliver.
After two seasons with limited progress under an indigenous coaching ticket, Munster decided for a total restructure that saw the experienced Rassie Erasmus come in as director of rugby above Foley. Erasmus picks the team and fronts the house. The buck stops with him.
Still dealing with the ramifications of the O'Connor decision, Leinster's hierarchy appear keen not to undermine Cullen after promoting him to the top job too quickly.
Over the summer, they paid Graham Henry a handsome consultancy fee for a two-week visit, and now they have brought in a coach with international head coaching experience to support their former captain.
Within the IRFU, there is a concern that they could lose two promising former professionals and provincial legends as a result of Munster and Leinster's fast-tracking of Foley and Cullen.
IRFU performance director David Nucifora was never too keen on Cullen's appointment, but the timing of O'Connor's exit meant that quality alternatives were thin on the ground.
The entire Leinster coaching ticket are out of contract at the end of the season and Lancaster, whose family will remain in Leeds for the duration of his nine-month stint, has not committed to remaining beyond the end of the season.
Yesterday, he repeatedly stressed that he is just getting to know the lay of the land in his new surroundings - an organisation that Cullen has been part of for the best part of 20 years.
He also becomes part of what Nucifora last May described as the "strong group of coaching intellect" in the Irish system and automatically joins the list of potential successors for Joe Schmidt as Ireland head coach if the Kiwi chooses to leave at the end of this season.
Of course, on his first day in the new job Lancaster wasn't about to go touting for bigger and better things and he said that "restoring Leinster to being a dominant European force" is his priority.
"Further down the line, opportunities might come up. It is not something I crave at the moment," he said of being a head coach again.
"I've got an opportunity to influence the group and pass on what I've learned in a coaching capacity.
"When I was trying to develop the (England) team and bring it on from 2011 and 2012, grow a young team, there are so many pieces to the jigsaw that it will be nice to go back to doing what I really set out to do as a coach in the first instance, and that's just hands-on coaching.
"Leo knows this club far, far better than me; I've still yet to meet the players properly individually, I don't know them all and I don't understand the club and the culture, so I'm 100pc happy with the role I've got.
"As for what the future holds, we'll see, but I ain't thinking about that too much for the time being."
Last season, Johnny Sexton went public with his criticism of Leinster's regression since the glory days under Michael Cheika and Schmidt, particularly with regard to the culture of the organisation.
Henry's appointment appeared to be a response, while one of the core strands of Lancaster's England tenure was around re-building the team's culture after a post-2003 World Cup regression.
It didn't end the way he wanted, but he believes that that work has come to fruition under Eddie Jones.
That emphasis on culture and the way Lancaster carries himself were surely part of Leinster's desire to appoint him. Yet, as a No 2, it is questionable that he can have that much influence on the overall structures; that is the role of the top man.
As for Cullen? If Leinster progress this season, much of the credit will go to his new assistant. If they don't, he himself will carry the can.
Yesterday, he and his new 'senior coach' sat by side by side smiling. This time next year they might well have swapped places.