Much like his catalogue of mercurial innings, McCullum's reputation as a captain has seldom settled. Rarely have perceptions around a New Zealand sportsman generated such a spectrum of applause and derision.
To counter the accolades, McCullum was subject to public fury after Ross Taylor's ousting as captain, his debut test at the helm coincided with the Cape Town 45, he threatened to sue John Parker for defamation, and testified for the prosecution in Chris Cairns' perjury trial.
However, McCullum became a player whose force of personality appeared to draw stronger performances from his charges, coupled with a culture of humility. Nothing appeared taken for granted, no sense of entitlement inadvertently seeped in with success.
It's not time to lurch too far into obituary mode because three limited-overs series and two tests against Australia await. In the latter he will, if fit, become the first of 2804 test representatives to play 100 consecutive matches from debut, a staggering nod to endurance.
The 34-year-old already risks becoming Quasimodo in his retirement village. His back regularly requires painkillers before play and must baulk every time a boundary looms into view.
McCullum is a candidate for the crown of New Zealand's greatest cricketer but that is based on one slow-burning condition: the incumbent side must build a dynasty to sustain their world-class performances across generations.
Sir Richard Hadlee is safe in his status for now, but the goodwill generated from hosting and almost triumphing at the World Cup - when McCullum claimed his side were having "the time of their lives" - should pay significant dividends.
"Dynasty" is a bold term and one New Zealand Cricket can never claim to have had.
The 1980s gifted an era in which fans have wallowed, but it was principally led by two great players, Hadlee and Martin Crowe, and reinforced by a wily band of professionals in a largely amateur era.
Successes during 1999-2003, a period which boasted the talents of Stephen Fleming, Chris Cairns, Mark Richardson, Shane Bond and Daniel Vettori, was a further false dawn.
Fleming has long fostered a mentor-friend relationship with McCullum since his playing days.
"He's experienced some phenomenal growth [in the captaincy role]," he said during the World Cup. "We talked about the style he wanted early on, but since then it's been his relationship with Hess [coach Mike Hesson] that's developed. I love talking to him about the game, but it's more as a mate.
"The emergence of the current talent is perfectly timed with the rise of an aggressive captain. I don't think a New Zealand team has played this well and been so complete.
"They now believe they're one of the best sides in the world. It's a bit like the All Blacks' model where they've got some of the world's best in key spots and feel they can be competitive against any opposition."
Likewise, Vettori lauded McCullum as the key to team morale during his final test in Sharjah, a victory that coincided with Australian representative Phil Hughes' death in Sydney.
"Brendon allowed everyone to grieve in their own way. There was no pressure on anyone to do anything. I think guys accidentally relaxed from that and played with a lot of freedom."
McCullum has revolutionised how New Zealand play; with goodwill but aggressive intent. Public apathy has been consumed by fervour. He deserves credit for balancing the needs of senior pros, in particular Taylor, while convincing younger players they belong at international level.
He deserves to retire to stud, Vermair Racing to be specific, and have the time of his life.
