What I liked best about New Zealand's defeat of Australia - apart from the fact that Australia lost - was that New Zealand saw their basic tactic demolished before their eyes. So naturally they stuck to it, and won.
The Kiwis have become everybody's second favourite team at the World Cup because they are dynamic and dashing and daring and they seem to be reinventing the game every time they play it. Their policy of all-out-attack reduced Australia to 106 for 9. In their first 30 overs, the captain, Brendon McCullum, used up his three top bowlers: how's that for commitment?
Let's call it the Doggy Scale: a system for measuring aggressive intentions in sport. New Zealand have been at the Rottweiler end of the scale throughout, while England, as a fascinating, not to say despairing antithesis, are operating the spayed Labrador method.
New Zealand bowled Australia out for 151 and set out to finish them in as few overs as possible. The other day they went past England's score in 12.2 overs while England thumped their tail on the hearthrug and then rolled over to have their tummy tickled.
But this time New Zealand's Rottweiler policy didn't come off. It began well enough as McCullum hit 50 from 21 but they then collapsed from 131 for 4 to 146 for 9. So what do you do with six runs needed to win and one wicket in hand? England would have nudged and nurdled and tried to get them in singles, probably losing with a run-out. Kane Williamson kept up the Rottweiler tradition and got them in a single blow.
It's a wonderfully eye-catching way to play sport, and there's a part in all of us that wants it to succeed. It sometimes seems that that is the morally correct way to play: as if cunning and coolness was not a legitimate part of sport. In the 1996 World Cup, Sri Lanka played with what passed then as dementedly aggressive batting with the brilliant Sanath Jayasuriya. This revolutionised the game, even though his stats look pretty humdrum these days.
Aggression looks like the way forward in the 21st-century game, especially when you compare it with the results gained by the fat-Lab tendencies of England, who still think one-day cricket is rather a daring innovation. They played Sri Lanka on Saturday and genuinely imagined that 309 was an impregnably brilliant score. They think they are still playing Gillette Cup cricket back in the 1960s.
Sri Lanka beat them with nearly three overs to spare, and for the loss of one wicket. England weren't outplayed. They were playing to an outdated philosophy of one-day cricket, building their hopes for a winning total round Ian Bell's leave shot.
England's passivity is out of date. The question is whether New Zealand's hyper-aggression is the way forward. Batting once thought extraordinary is now standard practice. We are no longer shocked by big innings from McCullum, Chris Gayle and AB de Villiers.
But the same level of aggression is now being expressed by the captain of the fielding side. McCullum has been a prime mover in this shift. It's as if the cricketing world had suddenly worked out that when a batsman is out he can't score any more runs.
Take New Zealand's policy with Michael Clarke, the Australian captain. England would have worked out his favourite areas for scoring and tried to block them all off. Trent Boult bowled to him with two slips and two more catchers at short extra cover - and one of these, Williamson, held the catch that dismissed him for 12.
Suddenly one-day cricket is more like real cricket. The bowler is no longer just teeing it up for the batsman while hoping not to concede runs in double figures per over. The will of the captain has restored the balance between bat and ball and made one-day cricket rather more than a six-hitting competition.
The question, in this very long competition, is whether New Zealand can sustain this intensity. McCullum is a man who likes to make one heap of all his winnings and risk it at one turn of pitch and toss. But sometimes such a policy can go amiss at the quarter-final stage.
There is also New Zealand's traditional small-nation sense of one-downness, a condition they suffer from in every sport except rugby union. As a matter of fact - though don't tell them I said so - it has been in evidence even there, as they went for 20 years between World Cups. It'd be a sad thing to see the cricketing Kiwis lose their nerve - or push their luck too far - at the sharp end of the tournament.
New Zealand are remaking cricket: so naturally there are plenty of people who don't believe it can work. That's always the way. "I think there is a world market for about five computers," a remark attributed to Thomas J Watson, chairman of IBM in 1943, and if you'd like another: "There is no reason for anyone to have a computer in their home," said Ken Olson, president of Digital Equipment Corporation in 1977.
So no, they'll never get it off the ground, they can't possibly go faster than a horse and carriage. But right now New Zealand are looking good, and what they are doing is the most fascinating thing in a tournament that's already twice as interesting as most of us expected.
To expect their comeuppance or to predict their ultimate success is not to judge the Kiwis, it's merely a way of revealing what kind of person you happen to be yourself. I'm enthralled by the way they are putting this new vision to the test, just as I was when Jayasuriya was doing his stuff back in Pleistocene.
And to reveal myself here, I'm on the go-boys side of the debate. I'd sooner have a Labrador in the house playing with the children, but you're better off with a Rottweiler when it comes to guarding it.