Ireland lock Devin Toner was the surprise omission from Joe Schmidt's 31-man World Cup squad Monday, as Jean Kleyn edged out the experienced Leinster man less than a month after making his international debut.
A near ever-present throughout Schmidt's six years in charge with 67 caps, Toner's lineout abilities were sacrificed for Kleyn's power up front after the South African-born lock qualified to play for Ireland just last month.
"I've coached Dev for 10 years and he's not just a lineout champion for us, he's such a good player and an absolutely quality person," said Schmidt in a statement. "That was an incredibly tough conversation.
"With Jean Kleyn, we probably don't have a specialist tighthead second row as such. It's a balance we're looking for across that squad of 31. Jean Kleyn fitted that and Tadhg Beirne gives you the versatility of both a second row and a back row."
Schmidt was able to name a strong squad after no major injury concerns emerged since flankers Sean O'Brien and Dan Leavy were ruled out at the end of last season, meaning reserve flyhalf Joey Carbery travels while recovering from injury.
It was a difficult thing... to have the 45 that we had. We went down to 40 players and to go from 40 down to 31 was really difficult but we had a process whereby we looked back through every training, looked through the games," Schmidt said.
"Some guys... obviously had more experience and probably had more credit in the bank and were more established.
"There were other guys who were trying to force their way into group and trying to get a balance of current form versus previous performance. It's always a very, very difficult conundrum to try to solve."
Luke McGrath was favoured to Kieran Marmion as backup scrumhalf, Rhys Ruddock pipped Jordi Murphy in the backrow mix and Will Addison was unlucky not to make it as a versatile option in the backs.
"If you're going to have a guy who was the quintessential team member, Kieran Marmion is the guy you would hold up as someone who has done fantastic stuff for us at scrumhalf," Schmidt added. "He's so versatile and such a good man to have.
"Conor Murray has been a world leading scrumhalf and Luke McGrath has been incredibly good this season. So the two of them in competition with Marmion was a very tough decision to come to."
Ireland, who face hosts Japan, Scotland Russia and Samoa in Pool A, will complete their preparations against Six Nations champions Wales on Saturday before they open their World Cup campaign against the Scots on Sept. 22.
Ireland Rugby World Cup Squad
Forwards: CJ Stander, Josh van der Flier, Peter O'Mahony, Rhys Ruddock, Jack Conan, Tadhg Beirne, Jean Kleyn, Iain Henderson, James Ryan, Rory Best (captain), Niall Scannell, Sean Cronin, Tadhg Furlong, Andrew Porter, Cian Healy, Dave Kilcoyne, John Ryan
Backs: Rob Kearney, Keith Earls, Andrew Conway, Jordan Larmour, Chris Farrell, Robbie Henshaw, Garry Ringrose, Bundee Aki, Jacob Stockdale, Johnny Sexton, Joey Carbery, Jack Carty, Conor Murray, Luke McGrath