There is always some tinkering, and it always seems to make sense.

Besides the evolution of the new centre partnership, ironically blocked at this World Cup by the revolving door of Robbie Henshaw and Jared Payne injuries, it's largely been 'as you were' for Ireland teams under Joe Schmidt.

But, in stark contrast to previous regimes, the door is never welded shut. Iain Henderson forced his way into the team of late while Devin Toner has been rewarded for last weekend’s career performance at Wembley with a bench role against Italy.

Injury profile

Jack McGrath and Cian Healy have traded places – largely due to the latter's injury profile – while Keith Earls and Luke Fitzgerald are included when fit enough.

“It’s nice to finally work with them,” said Schmidt of that wonderfully talented yet injury prone three-quarters, both Lions in 2009.

Patterns? Natural, make that durable, cover for Mike Ross has never been discovered. Still, be it Declan Fitzpatrick, Marty Moore, Rodney Ah You, Nathan White or Tadhg Furlong someone always has to relieve the big man around the hour mark.

“Last time I played an 80 minute game was against Australia last year,” said Ross. “I reckon Joe was full of opiates due to the pain in his side [his appendix needed removing later that night] and forgot to take me off. I like to think it’s still in the tank but given the squad we have there is no need for anyone to play 80 minutes. Jamie is a bit of a freak so is probably happy at that prospect.”

The only positions that have changed throughout the major games of the Schmidt era?

Tommy Bowe and Fitzgerald seemed untouchable as Grand Slam wingers in 2009 but injury has ensured some great days for others.

All told, the lack of major surgery on his XV highlights Ireland’s sparse player pool while enhancing their achievement.

Ireland's evolution under Joe Schmidt

v New Zealand (Aviva stadium - L 22-24, November 2013)

Luke Fitzgerald runs at outside centre when O'Driscoll gets concussed while Schmidt goes for Leinster disciples – Kevin McLaughlin and Mike McCarthy – in some tight selection calls. That changed as players from other provinces learned the bible. IRELAND: R Kearney; T Bowe, B O'Driscoll (L Fitzgerald), G D'Arcy, D Kearney; J Sexton (I Madigan), C Murray; C Healy (J McGrath), R Best (S Cronin), M Ross (D Fitzpatrick); D Toner (M McCarthy, P O'Connell; P O'Mahony (K McLaughlin), S O'Brien, J Heaslip.

v France (Stade de France - 22-20, March 2014)

Confirmation of Iain Henderson's huge future evident when tearing off that final scrum as the French attack is unceremoniously halted. Ian Madigan repays faith shown in him by doing a sound job when coming in for a concussed Sexton. Same goes for Jack McGrath. IRELAND: R Kearney; A Trimble, B O'Driscoll, G D'Arcy (F McFadden), D Kearney; J Sexton (I Madigan), C Murray (E Reddan); C Healy (J McGrath), R Best (S Cronin), M Ross (M Moore); D Toner, P O'Connell; P O'Mahony (I Henderson), C Henry, J Heaslip.

v South Africa (Aviva stadium - 29-15, November 2014)

The new centre partnership delivers in emphatic fashion. The one big, perceived, selection risk of the Schmidt era pays out as two fullbacks seamlessly switch to a new life in a traffic-congested midfield. Rodney Ah You makes the briefest of cameos as needs must. IRELAND: R Kearney (F Jones); T Bowe, J Payne (E Reddan), R Henshaw, S Zebo; J Sexton (I Madigan), C Murray; J McGrath (D Kilcoyne), S Cronin (R Strauss), M Ross (R Ah You); D Toner (M McCarthy), P O'Connell; P O'Mahony (T O'Donnell), R Ruddock, J Heaslip.

v Scotland (Murrayfield - 40-10, March 2015)

The importance of Cian Healy and Sean O'Brien, especially if Ireland are to reach a World Cup final, is emphasised in this demolition, riddled with offloads, as Ireland switch to Plan B to rack up the necessary points difference needed to retain the Six Nations title. IRELAND: R Kearney; T Bowe, J Payne, R Henshaw, L Fitzgerald; J Sexton (I Madigan), C Murray (E Reddan); C Healy (J McGrath), R Best (S Cronin), M Ross (M Moore); D Toner (I Henderson), P O'Connell; P O'Mahony, S O'Brien (J Murphy), J Heaslip.