How long is a piece of string? When is the ideal time to hand a young rugby player his senior international debut?

There is no finite measurement for either conundrum but in the case of the latter there are parameters, the principal one of which is the number of appearances at provincial level.

Ireland play four Test matches (New Zealand twice, Canada and Australia) during November. But injuries notwithstanding the only time coach Joe Schmidt will have a little wriggle room to ‘experiment’ in personnel terms is in the match against the Canadians.

The draw for the 2019 Rugby World Cup takes place next May so ranking points garnered from each match are so important in ensuring favourable positioning when the balls go in the drum. Eight of Ireland’s nine matches before then are against Tier One nations – Canada are the exception – and six are at home where the world ranking points’ co-efficient can be punitive for losing.

The facility for Schmidt to blood players is limited; one game against Canada and then in all probability two Test matches in Japan and the possibility of a game against the USA being added to that schedule next summer. It’s a lengthily hiatus.

Second Captains

There are obvious contenders amongst the tranche of promising young Ireland players that have earned the right to be considered for the Canada game. But is there a formula, incorporating age and provincial appearances that can offer a guideline to the Irish team management outside of form, talent and the experience profile required in some positions over others?

As the adjoining graphic illustrates, the combined total of appearances for their respective provinces of the last 10 players to be capped by Ireland under Schmidt at the time of that debut is 410; it works out at a neat 41 appearances as a benchmark.

That number is skewed a little by the fact Connacht’s Matt Healy had played 69-times while the second highest contributor, Munster’s CJ Stander (66) would have represented Ireland sooner were it not for the three-year residency rule.

If you take out the two highest numbers then the average plummets to about 34 caps, which is a more representative mean.

In blue

Going a little further back and not sequentially, Jack Conan had 23 appearances for Leinster when making his debut against Scotland in 2015, Connacht scrumhalf Kieran Marmion (28), Ulster centre Stuart Olding (16) and Paddy Jackson (32); the exception was Iain Henderson who played just six games for Ulster before being capped against Scotland in 2013.

A tighthead prop or an outhalf may need more experience and game time at provincial level before making the step-up to international rugby. Joey Carbery (9) might disprove that assertion if he makes the match day squad for the Canada game. He’s been so impressive in the way he’s handled everything to date.

Leinster’s Garry Ringrose (29) is the young player with the most irresistible credentials and would appear a shoo-in to win a first cap at some point in the next couple of weeks. There are others like Munster number eight-cum-flanker Jack O’Donoghue (42) and Connacht wing Niyi Adeolokun (37) who are in the ball park, experience wise.

Munster duo John Ryan (80) and Billy Holland (138) were included in a 34-man extended Ireland squad announced yesterday evening as was Leinster hooker James Tracy (23) and scrumhalf Luke McGrath (57).

Leinster flanker Dan Leavy (21), Munster wing Darren Sweetnam (17) and Connacht fullback/wing Cian Kelleher (14, seven for Connacht and seven for Leinster) are young, in-form and quickly building not only a portfolio of experience but demonstrating the aptitude to excel in the European Champions Cup, something not too far removed from playing a Tier 2 country.