Has any new New Zealand captain in a major sport undertaken such an enormous - or utterly hopeless - task? McCullum is leading a mob of virtual nobodies by international standards against a ruthless foe, the best team in the world, who revel in a fightback as much as they do grinding opponents into the dust.
Even if New Zealand has the odd good session, or the odd good half session, or the odd good over, South Africa are not a team to cower, as we saw when they clung on in the tough times then engineered a remarkable series victory in Australia.
The ICC rankings aren't the be-all and end-all of judgments. But they do indicate general form and the test story alone makes ugly reading for New Zealand. South African players are dotted around the top of the categories while the only New Zealanders to get a look-in - Ross Taylor and Daniel Vettori - aren't touring. This ain't David versus Goliath - this is Dave's little brother versus a Goliath Army.
It still seems amazing that an emergency intervention hasn't at least been tried to hoist Taylor over to South Africa, because this is a crisis worthy of a mercy dash. But Taylor's non-appearance adds to the image of McCullum the underdog, and we all love to root for an underdog.
McCullum has come across quite well during the Taylor-Mike Hesson disaster, as gracious, sensible and genuine. But he is in for one hell of a mauling when the cricket action starts and if he falls to poor shots as can be his way, the critics will have a field day analysing a captain who is not leading by example.
To steal a T20 phrase, this tour is set to be remembered as the Big Bash, leaving New Zealand's slide towards the perils of T20 gathering more pace.
Not that a T20 world is exactly a disaster for McCullum, or Taylor, for that matter. You have to wonder if Taylor would have been so quick to take a break without the Indian T20 riches as a handy backstop.
Lucky he won
On the weekend's Fight for Life ... Warriors wing Vatuvei should be relieved that he won a decision over Olympic rowing star Murray. Had a rough and tough leaguie lost to a mere rower, he could have been charged with bringing the 13-a-side code into disrepute.
Salute to promoters
I'm not a fan of home boffin boxing, but the time feels right to applaud the former Kiwi league forward Dean Lonergan, who is the event promoter. An entrepreneurial spirit should be at the heart of professional sport and Lonergan has been in the thick of it since prematurely retiring as a player.
He started off by bringing Australian club league sides here for one-off games at a pivotal moment in the sport's history, when New Zealand needed to latch on to the booming Aussie game. I well remember the hopeless old New Zealand Rugby league looking through a green eye at Lonergan's efforts - having failed to do anything significant itself, the board considered trying to cash in on his work by charging a licence fee.
Okay, so the promoter is out to make a significant buck for himself. But promoters face significant risks allied to lots of hard work and Lonergan hasn't always come out on top.
His latest venture, a glamour NRL league nines tournament at Eden Park, sounds like an entertainment winner with wider value for Auckland and reveals again his well- developed understanding about sports promotions and publicity. His techniques still reflect a lesson I witnessed him delivering in the NZRL boardroom a few moons ago, that promoting star personality versus star personality is the way to draw a crowd. For the nines tournament, he wants the sport's big names here, in contrast to the Wellington rugby sevens.
The bottom line is this: without risk-takers with ideas like Lonergan, we'd be a lot worse off. So, a salute to the promoters.
