Read also: Playing the field: SBW
Kent said Williams "felt used" and tensions spilled over within the Williams camp shortly after a brief cameo off the bench in the All Blacks' 30-14 win over the Wallabies at Eden Park in August 2011.
"Williams was in no mood to celebrate with this teammates," Kent wrote in the unauthorised biography. "He headed home to the hotel where Nasser [his manager Khoder Nasser] was staying with Anthony Mundine and Quade Cooper. Williams turned up, still in his [All Black] socks and shorts. That was as good an indication as any at how angry he was.
"'F*** him bro', Mundine said. He was talking about the coach, Henry. 'Let's go get on a plane. Let's go shopping in LA. You need some new clothes. He's got the world's best player in his team and he leaves him on the bench. Who the f*** does he think he is?'.
"Mundine pulled out his mobile phone. 'I'll book the tickets now, bro, we can be on a plane in the morning'. Nobody, it seemed, was doing anything to calm Williams."
Williams' problems with Sir Graham centred around the coach's preference for proven test star Ma'a Nonu.
His management's relationship with the New Zealand Rugby Union was also strained over the sporting body's decision to block a hoped-for lucrative endorsement deal as it clashed with one of the sporting body's official sponsors.
When Williams linked with the NZRU in late 2010, Kent said "his one stipulation" was that he would be picked for the All Blacks if his form warranted it.
"Williams would later admit he felt 'lied to'," Kent wrote. "Sonny always tried hard to stay true to the core values of the team. This was one of the few times the mask slipped."
Tensions between Williams, his close team of allies, and Sir Graham continued almost right up to kick-off of the World Cup.
"Just 13 days before the World Cup Mundine had tweeted to Williams: 'Bra the more I think of this bulls*** the more I think I gotta get yu out of that environment'," Kent wrote. "For a man driven by achievement like he was, his limited role in New Zealand's World Cup did not sit well. He did not feel part of it."
Even before Williams' limited game time with the All Blacks, Kent claims the midfielders' relationship with rugby bosses "nearly fell apart".
"By now Sonny was no longer feeling the love," Kent writes. "When the NZRU rejected a private sponsorship agreement the noise grew.
"Reports in New Zealand raised fears the fallout between Nasser and the NZRU over the deal would see Williams leave the code."
Williams was already raking in an estimated $2 million a season from his NZRU contract, plus endorsements with Rebel Sports and adidas.
Sonny Ball - the Legend of Sonny Bill Williams also looks at Williams' league and boxing careers.
The book's cover features a caricature of Williams, as publisher MacMillian Australia was not able to get permission to use a photo of Williams on the book's front.
Nasser last night told the Herald on Sunday that neither he nor Williams would comment on the unauthorised biography.
Williams has been fodder for media on both sides of the Tasman since his NRL debut in 2004. His personal life has also dominated headlines including his switch to Islam in 2008, his secret marraige to Alana Raffie in 2013 and the birth of their daughter, Imaan, last November.
