This year, he's been in scintillating form
Sonny Bill Williams will leave a legacy in Rugby Union unlike any other Rugby League convert.
This is the general consensus after Williams completed his All Black duties with a 22-0 shut-out of the Wallabies in Auckland on Saturday - a match which not only put the Kiwis in pole position in the Rugby Championships, but also ensured New Zealand retained the Bledisloe Cup for a 10th straight year.
Williams admitted to mixed emotions, following an emphatic All Blacks swan song on Saturday.
However, he felt a Super Rugby championship and a Bledisloe Cup triumph have made his departure an easier pill to swallow.
Williams will honour a promise to switch back to the NRL next year, after a stint in Japan, but has made it clear in recent weeks he's having regrets about leaving Rugby Union just as he's started to become an unstoppable force with his power running and unique ball skills.
The dynamic No.12 toyed with the Wallabies on Saturday.
Williams says he hopes he'll one day pull on the black jersey again but said if he has indeed played his last rugby Test, he can be satisfied.
"Winning [the Super Rugby title] with the Chiefs and [the Bledisloe Cup with New Zealand] tonight has made me a little bit more happy leaving in that sense," Williams told a media gathering in Auckland.
"But when you form friendships and close friendships, it's always tough to leave.
"... You're only caretakers of the jersey and you want to leave it better than when you've found it."
Williams thought he'd played his final Test against Ireland in June before getting a late call from coach Steve Hansen to play a part in the opening Rugby Championship fixtures against Australia.
The 27-year-old said it was after the Irish series and he was out of the team's inner circle when he discovered how much he'll miss being an All Black.
Williams added that he hoped that he had left a mark as an All Blacks second five-eighth.
“You're only caretakers of the jersey and you want to leave it better than when you've found it,” Williams said.
All Blacks coach Steve Hansen compared him to another well-known dual international, and said that the World Cup holders would welcome back the midfielder.
“…Over the past 12 months, he's learned and got a game understanding very much like Brad Thorn," said Hansen.
"This year, he's been in scintillating form. It's a shame he's going but we all understand why he has to and we're supportive of him and looking forward to him making a decision to come back as soon as he can."
Williams said it had been satisfying to win the Bledisloe Cup and he said the wrench from leaving the All Blacks had been most noticeable after the Irish series when he felt he had played his last Test.
"Every week we get in a bit of a huddle and the skip says 'There's a lot of men out there who want to get involved in this circle. I guess you feel it but you don't really understand it until you are outside of that circle and to get the call from Shag [Hansen] to come back and help out, I said, 'the dream's not over'. That's how I felt," he said.
And the last two weeks he had put the emotions to one side and focused on doing his job.
"It's going to be tough leaving the boys."
And he added the door hadn't been shut on possibly coming back to New Zealand and putting his hand up to be considered for the side again.
"When you form friendships, close friendships, it is always tough to leave, so who knows?"
Sources: allblacks.com & NZ Newswire