Join us at 2pm for the live announcement of the All Blacks World Cup squad
While attention is focused on who will get the cruellest cut at 2pm today - with Hosea Gear and Liam Messam tipped to be the highest-profile casualties - the All Black selectors' hardest decision could come later when they're forced to choose their first-choice fullback for the World Cup.
Israel
Dagg did more than announce his return from injury with a standout display in a poor All Black performance at Port Elizabeth, he stood up on a big stage and shouted "it's my time".
The ease with which he sliced through the Springboks' ultra-committed defensive line and glided downfield was Cullenesque. And it is Christian Cullen that can provide a salutary lesson of what goes wrong when a player is not picked in his position at or near the peak of his powers.
Cullen had carved out a reputation as the best fullback in the world when he was sent to the 1999 World Cup as a centre. That move was designed to accommodate Jeff Wilson at fullback, which in turn allowed the combined talents of Jonah Lomu and Tana Umaga to roam on the wings.
Cullen was never as effective again and by the time 2003 rolled around injury had robbed him of half a yard of pace and he was not picked.
The consequences of not giving Dagg his head next month are not so dire. His competition for the No 15 jersey happens to be a 97-test veteran that has rarely put a foot wrong.
Even so, Dagg's Hawkes Bay coach believes that unless the All Blacks are desperate for Mils Muliaina's seniority at the back, it is Dagg's time to shine.
"I think so," Peter Russell said. "He's now the Mils of old, really: he's good in the air, he's taking the gaps, he's putting in raking kicks.
"Mils is a good kicker and an intelligent footballer still and they probably need a bit of seniority at the back, but I think Izzy's grown a hell of a lot in the last couple of years."
Dagg's reputation at the Highlanders was that of a prodigiously talented kid who was going to have to choose whether he wanted to be the life of the party or an All Black.
Too often they were hearing what Dagg was getting up to of an evening from members of the public. What they were hearing did not gel with Dagg's stated occupation of a "professional" athlete.
"He was just a young kid really," Russell said. "He's grown a lot. When Zac [Guildford] made the All Blacks in 2009 and he missed out while Ben Smith got in, that gave him a kick up the bum and away he went."
The Crusaders had won a reputation as a team that maximised talent by emphasising character, so it was no surprise he was attracted to the franchise.
What was surprising was his calculated decision not to flat with long-time sparring partner Guildford. It sent an immediate signal that Dagg was about to get serious about his rugby.
