Versatility key for World Cup bid
Des Berry on how squad restrictions favour certain players
Versatility can be a dirty word in rugby. The greats of the game are almost always identified by the number on their back.
How many people have seen those photos from behind of a muddied green shirt with the number thirteen? It could only have been Brian O'Driscoll.
The same goes for Richie McCaw (7), Dan Carter (10), Lawrence Dallaglio (8), Serge Blanco (15) and on and on.
The mastery of a craft can only truly be attained when it is given all your focus.
There are the masters, the greats.
There are the good men that surround them, those you can depend on, the mainstays of international rugby.
Then, there are those who have to compromise their personal dreams to reach their personal goals.
The 27-year-old crossed the Irish sea from the North of England to Ulster in pursuit of international status and a place at the World Cup.
Primarily an outside centre, he has a good handle on a number of positions, including wing and full-back, where he will start against Wales this afternoon.
Coach Joe Schmidt has even nominated Addison as an out-half option should Jack Carty go down.
In the final analysis, it is this cover-almost-all cure that can be decisive, measured against someone limited by being a specialist.
"I think throughout my career, I've always done a couple of positions," he said. "I don't really see it as something that I desperately want to specialise because I just want to be involved.
"At the moment for me, it's not about specializing.
"It's about enjoying any opportunity I get in whatever position it is and using that experience as a positive wherever it impacts on another position further down the line.
"I just enjoy whatever is thrown at me."
The Munster back-five forward follows two impact involvements with a shot from the start on the blindside.
Beirne came into the professional world as an under-sized second row forward with a unique skill-set, a nose for the ball and enough pace to make him equally adept as a loose-forward.
The talent to play these two positions, and even number eight, is what makes Japan utterly attainable.
Last week, the speculation grew that Jean Kleyn had moved into pole as the fourth lock beside James Ryan, Devin Toner and Iain Henderson.
Ordinarily, this would make Beirne an outsider, were it not for his ability to fit the mould of the versatile back five forward.
"I have to be ready for any position," stated Beirne.
"I was on the bench for the back-row last week and I was put into lock because I've been asked to cover those positions.
"It's just about being prepared and knowing my role in all of those positions, just being comfortable in it.
"I'm more than happy to play in any of them."
It looked like the Leinster tight-head was in trouble when John Ryan put in sterling, set-piece work last season.
Joe Schmidt has claimed Garry Ringrose's experience at playing out-half in school - he was predominantly a wing or centre - makes him an option at out-half, at least for this afternoon.
The coach doesn't have to stretch that far back for Porter, who was the Ireland U20s loose-head when they reached the World Cup final in 2016.
In fact, he is a relatively recent convert to three and, if anything, has been undermined in his development by playing as Tadhg Furlong's understudy at Leinster and Ireland.
It was Furlong who earned one of the last seats to the 2015 World Cup as a dual-purpose prop without the requisite experience at loose-head. Now, it would appear Porter's fine scrummaging work in the first-half against Italy has convinced Schmidt of his versatility.
The Ulster loose forward has made a career out of his Jack of all Trades talents.
A simple examination of his international caps reveals 28 appearances in green, 15 from the off.
Of those, there have been seven starts at seven, five at eight and three at six.
This is a proven track record at filling in wherever necessary based on his dynamic, all action, accurate work allied to a strong presence at the breakdown and fine agility at the lineout.
The move from Dublin to Belfast last season was done in the name of making it to Japan. It looks like the right choice right now.
WALES: H Amos; O Lane, S Williams, O Watkin, S Evans; J Evans, A Davies; R Carre, R Elias, S Lee, A Beard, B Davies, A Shingler, J Davies, J Navidi (capt). Replacements: E Dee, R Evans, L Brown, J Ball, R Moriarty; T Williams. R Patchell, J Holmes.
IRELAND: W Addison; A Conway, C Farrell, B Aki, J Stockdale; J Carty, K Marmion; D Kilcoyne, N Scannell, John Ryan, I Henderson, James Ryan, T Beirne, P O'Mahony (capt), J Conan. Replacements: R Best, A Porter, T Furlong, D Toner, J Murphy; L McGrath, G Ringrose, D Kearney.