It probably doesn't help that first five Gareth Anscombe tends to play deep in the pocket - Nonu's best work has been with Dan Carter playing flat.
The All Blacks have the luxury of an in-form Sonny Bill Williams to use at second five-eighths during the three test Irish series. In some ways, the situation is a relief, as Williams will benefit from an extended run in his preferred position.
Ideally, the All Blacks would like Williams to play out of his skin in June to see if that can help Nonu reach his best form, as it did in World Cup year. The fate of Piri Weepu would appear to be similar to that of Nonu.
The country's portliest halfback is expected to be named but, like Nonu, may have to accept limited game time as Andy Ellis and Aaron Smith appear to be the respective No 1 and No 2 halfbacks. Some might question whether Weepu deserves to be in the All Black mix after his troubles this season which began when he reported for duty considerably overweight. He has been nowhere near the same player he was during the World Cup.
But that hasn't deterred All Black coach Steve Hansen, who is confident Weepu is coming right and that the versatile halfback has a proven track record of delivering in a black jersey.
This pattern is not new. In 2010 and 2011, Weepu was out of condition and out of form for most of Super Rugby. Once he came into the All Black camp, however, he shed some weight, improved his conditioning and, with his confidence boosted by a coaching panel who had faith in him, his performances began to dramatically improve.
Hansen is hoping the same will happen in 2012. In fact, Hansen is effectively prepared to take a calculated risk with all the under-performing senior All Blacks at the Blues.
Keven Mealamu and Ali Williams have also been quiet this season but Hansen has seen in the past how the latter in particular has transformed once he's in the national team.
Hansen, having been assistant coach for eight years, is also aware that it's not a new scenario for one New Zealand Super Rugby team to have its dramas and for everyone to fret about test players being dragged down.
"It was the Hurricanes last year," says Hansen. "We saw that with Cory Jane. He didn't play terribly well by his standards during Super Rugby and people weren't sure why we picked him. But he was outstanding for us. The thing about Ali is that we know in the past that he's come into our environment and played well."
Hansen speaks with the confidence of a coach immersed in test football. He's been involved in a coaching capacity for more than 120 tests and has a solid take on how much can be achieved in a few short training camps and five days of preparation before playing Ireland.
Just getting out of the Blues camp for a few weeks may be all it takes for Williams, Mealamu, Nonu and Weepu to play like their former selves. The latter two proved that last year when they both made the IRB Player of the Year shortlist after a torrid Super Rugby campaign.
Assuming both Weepu and Nonu come right with the All Blacks, it begs the question about their longer-term futures. This bust and boom pattern can't go on forever - at some stage, they need to deliver for their Super Rugby franchise.
But have they already become tainted goods? Weepu has said he would consider returning to the Hurricanes if the chance arose. The Hurricanes appear reluctant to take him back and perhaps with good reason. What's in it for them?
They have the up and coming TJ Perenara who is forming an outstanding partnership with Beauden Barrett.
The Chiefs and Crusaders don't appear to need No 9s and Weepu may have to commit to the Blues or persuade the Highlanders to take him.
Nonu hasn't given much away about his plans for 2013. Like Weepu, he signed only a one-year deal with the Blues and may be tempted to extend his stay to give them better value than they have had from him.
