They are the pulse of the side. Not necessarily the captain - indeed relatively rarely - but they're at the core of the operation in the field, the gee-up guy keeping fielders on the job.
Luke Ronchi reckons it's relatively easy to detect when things aren't spot on.
"Everyone knows," he said yesterday. "You can feel a presence if people aren't quite up or haven't got that energy.
"Baz (captain Brendon McCullum) is the same. He can tell. Once you get to that position someone needs to start talking, get them worked up."
He admitted during a series like the elongated seven-game rubber against Sri Lanka it can happen when faced with the same opponents so often you're just about on Christmas card terms with them.
"That monotony can hit in, but for something like this, I can't see how it's ever possible, how you can't be pumped up for a game."
That "something" is the World Cup and be very sure Ronchi won't suffer from that.
His back story is well known but the bullet points are: Moved with his family to Australia at seven; made the West Australian side, hammered a 51-ball century against Queensland in the 2007-08 summer; played three T20s and four ODIs for Australia -including hitting a 28-ball 64 in the Caribbean - before falling down the pecking order; then decided to head home where he cracked the New Zealand team in 2013, becoming the first player to represent two test-playing countries since Kepler Wessels 20 years earlier.
This week a television reporter asked Ronchi if any of his family or friends "back home" ... that was as far as he got.
"This is home mate," Ronchi shot back.
During his brief Australian career, Ronchi played a T20 on the Melbourne Cricket Ground in January 2009. It was David Warner's debut, and the stocky opener helped himself to 89 in 43 balls off South Africa. Ronchi played under Michael Clarke, and alongside Mitchell Johnson and Shane Watson.
Back to the MCG. That's where the World Cup final will be staged on March 29.
New Zealand are among the favourites but have never reached the decider. Eight of the squad - McCullum, Kyle Mills, Dan Vettori, Tim Southee, Grant Elliott, Ross Taylor, Martin Guptill and Ronchi have played on one of the game's grandest stages.
Without getting ahead of himself - and this New Zealand group are big on that - does he dare to dream of a return to the 'G'?
"You definitely think game by game, but you need to dream about that stuff," Ronchi said.
"If you're not, what are you aiming for? You want to do well in the next game but you've always got to have an end goal."
It's no bad thing to allow the mind to wander, at the right time?
"Not at all mate, not at all."
Ronchi admitted he has those 'pinch me' moments. Try four years ago, when things were going pear-shaped in Perth. Be in the World Cup and among the favourites? You're having a laugh.
"The way things were going I could well not be playing anything at the moment. So to be in the position I am now is pretty awesome and I'm thankful for it all."
New Zealand should be pretty thankful too, now that his batting position is settled at No7, after a rocky patch opening in England a couple of years ago, plus by his estimation he's in the best form of his career.
BJ Watling has a lock on the test job but Ronchi, blessed with quick hands, has long been regarded as the classiest pure keeper in the country; now the batting is significantly strengthening his contribution.
This summer, Ronchi has scored 573 runs at 52 since hitting 99 off 83 balls against South African at Mt Maunganui in October.
Missed a maiden ton? No matter. Arriving in the middle at Dunedin's University Oval with New Zealand 93 for five against the Sri Lankans last month, he shared a world record 267 for the sixth wicket with Grant Elliott. Ronchi smeared 170 not out in 99 balls with 14 fours and nine sixes.
A 15-ball 32 not out rushed New Zealand home in Nelson. He scores fast naturally and he's content with his game and feels more at ease than he did a year ago.
"Even then, you feel you belong but you want to be doing more. With my batting I'm feeling really good.
"For the last 12 to 14 months, my confidence has been really good with my batting. When I'm going out to bat I still feel nervous, but I'm in control of what I'm doing. It's good to be in that mind frame."
- By David Leggat of the New Zealand Herald in Christchurch
