He was carrying the physical and emotional toll of an extraordinary 18-month period that began with a massively unsuccessful campaign with the Hurricanes which ended with him being sacked. Then there was the bounceback with the All Blacks where he won the World Cup and was nominated as an IRB Player of the Year. He was straight off to his Japanese sabbatical where he played 12 games - including one on Christmas Day - and back to New Zealand to endure another awful Super Rugby campaign with the woeful Blues.
Ideally, the Blues wouldn't have rushed Nonu into action. But as All Black coach Steve Hansen said: "The Blues were desperate and they needed to win. Ma'a was a big signing for them and they felt they needed to play him."
In late April the All Black selectors pondered multiple options for Nonu. They toyed with the idea of not picking him and telling him to rest completely in June - to go on holiday and not think about rugby at all - and then rejoin the squad for the Rugby Championship. But they concluded the best way to manage him was to pick him. If he was in the All Blacks they would have greater control and it was made clear to Nonu weeks ahead of the final squad announcement that he would not play in June.
Nonu has been in and out of the camp these last few weeks - training early in the week before being allowed home.
The intention is to spark him back to his best - to give him that space to regenerate and the sight of Williams playing well enough will have done wonders for Nonu's state of mind.
"He [Nonu] knew he needed to recharge his batteries," says Hansen. "Emotionally, mentally and physically and this was a good opportunity to do it. We have got Sonny playing so well and other people we needed to get a line on.
"He's [Nonu]starting to feel his old self again. Getting cheeky. It has been a tough old year for him and for those people that don't understand - rugby is both a physically and mentally draining game and he has played for 18 months solid."
The Rugby Championship is where it will get interesting - where the squeeze will come on, where tough calls will have to be made.
Williams has looked the part at second five and, through his time with the Crusaders and the Chiefs, has developed neat partnerships with both Daniel Carter and Aaron Cruden.
He's a player who holds the defence; they are drawn to him, which is inevitable when a 1.94m, 110kg battleship cruises into the midfield.
But a fully recharged Nonu is a lethal piece of machinery, too.
With 104kg packed on a shorter frame, he's the higher impact ball-carrier and, with 66 test caps, one of the treasured few who knows what's required when the pressure comes on.
He's not the erratic, error-prone player he was in his early-20s: Nonu has matured into an accurate and reliable footballer who doesn't take enormous risks the way he once did.
So what to do? And will the outcome impact upon Williams' longer term plans? Does he need to feel the All Black love to be persuaded to sign on for another year?
The key to this puzzle may lie in the prognosis of Richard Kahui's shoulder injury.
If Kahui is forced to have surgery, there will potentially be a vacancy on the wing which Williams could fill.
If Kahui is fit ... let battle begin. Williams and Nonu are great mates - and for the rest of 2012 it seems they are destined to be great rivals.
