Taken on tour in 2004, Jerome Kaino only made his test debut in 2006 and didn't become a consistent selection until 2008. It took Kaino almost four years to fulfil his potential.
Adam Thomson has taken some time, too, to convince that he belongs at this level. His effort against the Boks in Wellington was his best test yet and all but confirmed his place in the World Cup squad. He is the perfect replacement - capable of playing across the loose trio and making his presence felt.
Theoretically Messam is just as versatile as Thomson. The problem is he hasn't shown he's capable of making the same kind of impact. His general work at the breakdown was poor against Fiji and, in the 20 minutes Messam played off the bench in Wellington, he chased shadows. He couldn't find the pace of the game, couldn't get his hands on the ball and make a contribution.
It was painful to watch. Messam is the kind of player everyone wants to see succeed at test level. He is not conventional and his ability to win games, as has been highlighted by All Blacks coach Graham Henry, makes him a difficult player to leave out.
Points of difference are what the All Blacks are trying to collect; players with a touch of genius whose skills will shine at the most opportune moment. Messam is so nearly that player. But nearly doesn't cut it and, with Thomson the perfect bench man, the All Black coaches will be tussling with whether they should persevere with Messam.
They will be aware what their patience has brought them with Kaino and Thomson. Maybe Messam is only a few more games away from cracking it at this level. If they cut him now, will they spend the World Cup regretting it? Balanced against that is the more restrictive World Cup rules which mean there is significant risk to not carrying a specialist openside in the original 30.
Richie McCaw, Kieran Read, Kaino and Thomson could handle the entire tournament with a specialist openside - Daniel Braid, Luke Braid or Matt Todd - available should anything happen to McCaw.
The other option is recalling Victor Vito. The Wellingtonian has had some big games in the last few weeks and has the athletic potential to be world class. The doubts about him are his desire to hurt people and play with a touch of fury.
Port Elizabeth may be Messam's last chance to press for his retention. Having been around the world as much as he has, Read might be spared more travel. In which case Messam will almost certainly be asked to prove himself against a full strength Springbok team.