Besides outhalf, Joe Schmidt's heavily stocked Ireland squad is at least three deep in every position.
The reasoning is clear enough. Johnny Sexton should shake off calf bruising, which he exacerbated in Castres last Friday, to face Scotland in Murrayfield on February 4th.
Paddy Jackson is the only other 10 named in this 40-man panel.
Joey Carbery, who was capped in November, is not due back from ankle surgery until round three when France come to Dublin on February 25th so Ian Madigan is the next man up.
After helping Bordeaux Bégles to victory in Belfast last Saturday, Madigan is due to face Clermont Auvergne this Sunday so he even if the 27 year old was selected he would be unable to join Irish camp in Carton House.
Probability tells us that Madigan will be called up as since last summer Sexton has struggled with shoulder surgery, two hamstring tears and a calf problem.
Schmidt, under IRFU directives, will only be selecting foreign based players, like Madigan or Marty Moore for that matter, in the case of injury.
Moore, who faces his old province Leinster in the Champions Cup quarter-final, is kicking his heels for the next few weeks as Wasps have no game until February 12th.
Schmidt, again, has a clear pecking order when it comes to tighthead prop as Connacht's Finlay Bealham is currently ahead of John Ryan, perhaps Munster's most improved player this season, to understudy for Tadhg Furlong.
But this looks like a fluid squad. And it has to be as the Pro 12 trundles on with four rounds during the Six Nations (Munster have five games).
That leaves Munster worryingly under stocked at loosehead prop as Jame Cronin has a damaged thumb and Thomas du Toit is due home for the Natal Sharks preseason.
That said, Dave Kilcoyne will struggle to break up the Jack McGrath and Cian Healy duopoly.
But expect multiple injuries in the coming weeks. Schmidt is planning accordingly by bringing in as many bodies as the Carton training pitch can manage.
The starting XV all but picks itself but there is genuine competition for the replacements bench in every position (besides outhalf).
Ultan Dillane is a notable inclusion despite an ankle injury keeping him out of Connacht's key European battles in January while the amount of blindside flankers suggests that Iain Henderson will primarily cover second row.
There are five locks named with Donnacha Ryan the other major contender to partner Devin Toner against Scotland.
Injury to Sean Cronin, a bad hamstring tear, sees Schmidt turn to either James Tracy or Niall Scannell to cover for Ireland captain Rory Best.
Tracy, having played against Canada last year, is ahead of the uncapped Cork hooker.
Tommy O’Donnell’s consistently excellent displays at openside for Munster this season renews the pressure on Josh van der Flier but Sean O’Brien is expected to shake off his latest soft tissue niggle to reclaim the seven jersey.
If, as expected, Jamie Heaslip remains the starting number eight then CJ Stander will bring his stunning European form to the blindside flank.
That leaves an enormous battle between Jack Conan, Peter O'Mahony, van der Flier and the continually impressive Dan Leavy to make the match day squad.
Conor Murray will play scrumhalf but there an interesting debate has begun between Kieran Marmion and Luke McGrath.
The centre partnership of Robbie Henshaw and Garry Ringrose looks a certainty.
Tommy Bowe is a surprise inclusion after he was unable to force his way into the Ulster squad that played Exeter. Andrew Conway, like Rory Scannell, is a form selection but none of these men are expected to break into the match day 23.
Rob Kearney should have some credit in the bank from Chicago so Simon Zebo's try scoring season will see him play left wing as Andrew Trimble holds onto the 14 jersey.
But all this can and probably will change.
Ireland squad:
Forwards (22)
Finlay Bealham (Buccaneers/Connacht) 6 caps
Rory Best (Banbridge/Ulster) (c) 100 caps
Jack Conan (Old Belvedere/Leinster) 1 cap
Ultan Dillane (Corinthians/Connacht) 8 caps
Tadhg Furlong (Clontarf/Leinster) 11 caps
Cian Healy (Clontarf/Leinster) 62 caps
Jamie Heaslip (Dublin University/Leinster) (vc) 91 caps
Iain Henderson (Ballynahinch/Ulster) 28 caps
Billy Holland (Cork Constitution/Munster) 1 cap
Dave Kilcoyne (UL Bohemians/Munster) 17 caps
Dan Leavy (UCD/Leinster) 1 cap
Jack McGrath (St. Mary's College/Leinster) 36 caps
Sean O'Brien (UCD/Leinster) 44 caps
Tommy O'Donnell (UL Bohemians/Munster) 12 caps
Peter O'Mahony (Cork Con/Munster) 37 caps
Donnacha Ryan (Shannon/Munster) 43 caps
John Ryan (Cork Constitution/Munster) 1 cap
Niall Scannell (Dolphin/Munster) *
CJ Stander (Munster) 10 caps
Devin Toner (Lansdowne/Leinster) 42 caps
James Tracy (UCD/Leinster) 1 cap
Josh van der Flier (UCD/Leinster) 5 caps
Backs (18)
Tommy Bowe (Belfast Harlequins/Ulster) 67 caps
Andrew Conway (Munster) *
Keith Earls (Young Munster/Munster) 54 caps
Craig Gilroy (Bangor/Ulster) 9 caps
Robbie Henshaw (Buccaneers/Leinster) 24 caps
Paddy Jackson (Dungannon/Ulster) 19 caps
Rob Kearney (UCD/Leinster) 72 caps
Kieran Marmion (Corinthians/Connacht) 9 caps
Luke Marshall (Ballymena/Ulster) 9 caps
Stuart McCloskey (Ballynahinch/Ulster) 1 cap
Luke McGrath (UCD/Leinster) 1 cap
Conor Murray (Garryowen/Munster) 53 caps
Tiernan O'Halloran (Buccaneers/Connacht) 3 caps
Garry Ringrose (UCD/Leinster) 3 caps
Rory Scannell (Dolphin/Munster) *
Jonathan Sexton (St Mary's College/Leinster) 63 caps
Andrew Trimble (Ballymena/Ulster) 69 caps
Simon Zebo (Cork Con/Munster) 28 caps
*Denotes uncapped player
