It is a tricky business for Super Rugby coaches balancing the need to blood young players against gathering competition points. There is inherent risk in giving youth its chance when there is no certainty the player in question is ready.
The Blues are at this juncture with 20-year-old tighthead prop Ofa Tu'ungafasi. They have lost All Black Charlie Faumuina for the season, which has left them further exposed in a key position. Their scrum was under intense pressure against the Highlanders and while Angus Ta'avao hung on gamely, he was patently toiling in the final 10 minutes.
Tu'ungafasi was gutted to not make his debut. The Blues chose to battle on, coach John Kirwan later saying they couldn't risk injecting the younger man, as they didn't quite have the game in the bag.
It was difficult to understand the rationale; if there was reluctance to blood Tu'ungafasi, why have him on the bench?
At 1.95m and 130kg, the former New Zealand under-20 player doesn't lack for physical presence. He plays in a position where it is inevitable, almost preferred, that he endures some torrid evenings.
There is no other way to learn the scrummaging craft but to battle directly with an old stager who knows a mountain of tricks. But the reluctance to play him doesn't lie with his set piece work.
"Technically we are not worried about him at scrum time," says Kirwan. "We think he would do okay there but it's about his understanding of defensive patterns. We have a fit enough football team that we don't need to make changes because the props are tired.
"I don't have a philosophy of that anyway. If they look like they are running pretty well, we will keep them out there. We need to get Ofa up to speed on the finer points of the game. He's getting there - he's worked really well this week."
Other Super Rugby sides have been less cautious with young props. The Crusaders were regularly using Owen Franks when he was just 20 and the All Blacks picked him when he was barely 21. Ben Tameifuna, who preceded Tu'ungafasi in the New Zealand under-20 side, was thrown into the Chiefs last year when they ran into an injury crisis and by June, he was in the All Black squad.
Some of the older theories about front-rowers are proving not to be truisms any more. A new breed is emerging - young props now reach the professional ranks with several years of strength training behind them. They are stronger than their predecessors, better equipped to deal with the physical and technical demands of the role.
Kirwan has little doubt that patience will pay dividends. Originally, Tu'ungafasi was not part of Kirwan's plans for 2013. The giant prop was contracted from 2014 - this year being one for him to build his technical picture of the wider game while playing for his club and province. When other franchises came sniffing, the Blues had to sign Tu'ungafasi for this year or risk never getting him back. Now, with Faumuina out, they have had to bring forward those plans again.
"He'll get his time," says Kirwan.
"It would be really nice to be able to get him out there with no risk. But this is not the time to do it - if we were up by 25 points every week, we could do that, so when he put him out there, we don't want to expose him or the team. He is close. He'll get some minutes this year."