Super-coach Wayne Bennett consistently packed his teams with tough, hardened individuals at the Broncos, Dragons and Knights.
"I always say you need to have played three years and about 40-50 games before you know what the hell is going on out there," said Bennett.
"Until then, you can get the odd exception but it is a huge adjustment. If you have got too many in the team who haven't got [those numbers] up, that makes you even more vulnerable."
Bennett said there are "a whole lot of issues" with young players.
"[Generally] the less, the better; the more, the more fraught you are with the danger of not getting it right," he said. "You have to manage how you get them in, what position that come in, how long they might play for, how long they don't play. I like the older players because they know how to get the job done."
Warriors coach Andrew McFadden has had limited flexibility this season. He's made mistakes at the selection table — but injuries to an already green team put greater demands on young players.
"You can't teach experience," said Warriors prop Sam Rapira. "When I was coming through, I had a lot of senior guys around me and it made things easier."
Back rower Raymond Faitala-Marriner is one of the new breed.
"Maintaining your consistency is the hardest part," said the 22-year-old. "You can't really afford mistakes. And the main thing is the different thresholds under pressure and in those key moments. Obviously senior players who are experienced are able to handle that pressure and there are some boys who need to keep working on that."
Experience drives success. There are some freaks — Daly Cherry-Evans has always looked comfortable and Cameron Smith was playing Origin before his 21st birthday — but generally miles on the clock matter.
Nathan Friend made his NRL debut in 2002, at the age of 21.
"When I first started, I thought, 'I'm ready for first grade, give me a go'. But it's not until about 50 games that you start to understand the game and every game starts to slow down for you. Now you enter a game and you can see things in advance."