Former New Zealand international Shayne O'Connor simply puts it down to the conditions in the country.
"On the hot and drier days you don't see it much but on the muggy days there's a lot more swing," said the 40-year-old Hawke's Bay-born man, who lives on the outskirts of Clyde in Central Otago where he is running his business, Trail Journeys, on a disused railway line.
Point taken but when asked how does that explain Southee's new-ball partner and cup MVP leader, Trent Boult, blitzing Australian batsmen in the one-wicket victory in Auckland, a jovial O'Connor replied: "Every dog has its day so you have to factor that in."
On a more serious note, the former left-armer thinks Boult possibly catches "some sort of draught or breeze that is favouring lefties.
"It's a bit above me but that's the best way to explain it in layman's language."
Whatever the scientific explanation or myth, O'Connor is delighted to see the Mike Hesson-coached New Zealand excelling on their home turf.
The former Napier Boys' High School graduate belongs to the school of sticking to the 1st XI who are doing the damage game in, game out.
"It's six-of-one and a-half-dozen of the other," he said, endorsing the rest-and-rotation policy if players are nursing injuries.
He believes the "sub-fielders" of Kyle Mills, Mitchell McClenaghan, Nathan McCullum and Tom Latham should slot into Hesson's matrix with aplomb if the need arose.
"There's enough experience to cope with that.
"Net training is about the physical side of keeping the bowling going, so the rest is mental.
"It's clearly one hell of a mental struggle going on so all the squad members absolutely mustn't stop."
O'Connor endorses Hesson's balancing-act argument that if they rest in-form players now then what will be the impact on them when they run back on to the field three weeks later.
"You've got to keep going and back yourself on the positives rather than the negatives.
"No one will get injured and everything will be fine," he reckons.
So what should we make of the nervousness pervading the country now that the Black Caps are four wins from four games and have a predominantly unblemished record in the build up to the cup. If everything's going swimmingly surely something is bound to go wrong?
O'Connor replies: "That's a very New Zealand question to ask, isn't it?
"What if Australia or South Africa were coming through like that. What would we be saying? We'd be saying, 'Look at those guys going amazingly well. They are so good to watch'."
The former Otago Volts cricketer said Brendon McCullum and his men were thriving in their environment.
"I'm just loving it. This environment is breeding success," he said, revealing, as a cricket coach for children, he notices everyone talking about their national heroes keeping up a courageous fight in the World Cup.
O'Connor isn't sticking his neck out to label the Kiwis "outright favourites" to win their maiden world crown but sees them finishing in the top two to three considering, historically, they haven't ever been in contention.
Asked who he would like to see New Zealand face in the playoffs, he said: "Any of the easy teams would be great."
Ideally, he envisions South Africa as the semifinalists and Australia in the final.
"South Africa and Australia have tall, quick bowlers but other teams are not that rounded.
"India and Sri Lanka have fantastic batting line ups but, for World Cup standards, their bowlers aren't up there."
He believes, for a team to prevail, it's imperative that batting and bowling departments need to come to the fore.
Partiality aside, O'Connor said the lefties in any team bring an X factor to the mix.
"The left-handers are a little different in that they bring the subconscious part of the game, if you understand what I mean.
"Any team brings in left-armers just to change things up a bit.
"You have to have something different in cricket to be competitive. If you have left-handers up your sleeve then you'll win without even getting on the park."
He urges fans to converge on McLean Park, Napier, tomorrow for the pool B match against Afghanistan, not just to see a World Cup match, but to savour their adroitness and attitude.
"I watched them play Scotland in Dunedin and they were just wonderful individuals, signing autographs and mingling with fans. The chance to rub shoulders and talk to them is more the opportunity than just the World Cup," O'Connor says of the day/nighter.
