There's an advertisement running on New Zealand sports channels at the moment featuring Dan Vettori.

He is watching television when several of his New Zealand team-mates turn up, wanting to switch channels. Argument ensues. To cut to the chase, it finishes with Vettori putting his head in his hands and slowly shaking it.

It might not have been the intention, but when you consider his importance to the New Zealand cause, and the half-baked efforts of others in the team at various points this summer, it is amusingly appropriate.

In this week's second Test against Australia, starting in Hamilton on Saturday, Vettori brings up his 99th or 100th Test, depending on how you view the ill-starred World XI game against Australia in 2005. Include it, and Vettori's bringing up his ton this week; treat the relevant mark as nation against nation, it will happen in Bangladesh in a few months' time. Either way it's a remarkable achievement for the bespectacled allrounder, who joins the man he replaced as captain, Stephen Fleming, as New Zealand's only 100-Test cricketer.

There are statistics that bear testimony to his influence within the New Zealand game. Consider just one: Vettori's Test batting average is 30.9; in the period he has taken over the captaincy, 26 Tests beginning in November 2007, that number is 44.07. His bowling average is also fractionally superior in that shorter period. Therefore it is a short hop to contend that the 31-year-old seems to be thriving, in personal terms, with the leadership.

Recently a sports commentator posed the question: Is Vettori New Zealand's finest cricketer?

These sort of subjective topics are great for whiling away idle hours, but if there are firm and conflicting viewpoints, you usually don't get far. In this instance, the answer is no. Here's a handful of names to ponder, in rough chronological order: Bert Sutcliffe, John R Reid, Glenn Turner, Sir Richard Hadlee, Martin Crowe. You'll find any number of supporters to argue each of those players has credentials superior to Vettori's.

How does he sit among the finest spinners New Zealand has produced? Now we're talking.

The answer is, head and shoulders clear of the rest.

New Zealand does not have an especially rich tradition of spin bowlers. Only one other has got to 100 Test wickets, offspinner John Bracewell, who was an immensely competitive, combative player. In his prime, a team of Bracewells wouldn't lose many matches, but there would be plenty of trips to the match referee's room.

There have been three other left-arm orthodox slow men of note: Tom Burtt, burly and gifted, but a liability in the field, in the years after the Second World War; Hedley Howarth, who churned through a mountain of overs in exhausting conditions in the late 1960s and early 1970s on the subcontinent and in the West Indies; and Stephen Boock, a thoroughly competitive and humorous man, who once kissed the Eden Park pitch en route to one for a bucketload against Javed Miandad and his chums 21 years ago.

Vettori is not among the biggest turners of a ball. His strengths include flight and variations, accumulated wisdom gleaned from 13 years in the big time. He is a treat to watch at work. One of his strongest attributes is best seen in side-on replays of an over. He uses changes of pace, with no noticeable change in action, and to excellent effect. As they stretch out, or advance down the pitch, batsmen find they are not quite there.

At times Vettori has had to be more defensive than he might wish - a case of necessity rather than preference. Rarely has he marked out his run with 450 or more runs to work with.

One of Vettori's strongest attributes is best seen in side-on replays of an over. He uses changes of pace, with no noticeable change in action, and to excellent effect. As they stretch out, or advance down the pitch, batsmen find they are not quite there

So try this question for size: How important a figure has Vettori become to New Zealand cricket?

Tom Lowry and Walter Hadlee were the early giants of the game. Reid was captain on the occasion of New Zealand's first Test win, against West Indies at Eden Park in 1956; he added Test wins No. 2 and 3 in South Africa six summers later to his resume, and was a colossus of the game. Among his claims to a place at the game's top table in New Zealand was his longevity as a national selector. He wanted a say in who he was leading through the gate and got it.

Now Vettori is in the same situation: captain and selector. It is not a double role for which he has received universal support. His fellow selectors are coach Mark Greatbatch and former captain and batting champion Glenn Turner. One advocate in his corner is Reid, who knows why Vettori wanted the extra responsibility, and supports his right to a strong say in who walks onto the field behind him.

It is an old argument: should there be a clear line between the occupiers of the dressing room and those who put them there? How do players view their captain when they know he is one of those who hold the key to their immediate place in the side? Vettori has maintained he will make hard calls when required.

At this moment he is his team's best bowler, possesses among their safest pair of hands in the field, and is perhaps their most reliable source of runs. Throw in the captaincy and selectorial roles and he has a full plate. Remember, he was also doubling up as de facto coach during the gap between the departure of Andy Moles and the appointment of Greatbatch, although he didn't much care for the terminology and didn't feel he was doing anything differently in his handling of the team.

Vettori's significance to his country's game can be traced back to his debut, against England in 1997. There was no gentle introduction, no bedding-in period for New Zealand's youngest Test player, at 18 years 10 days. He bowled more overs than anyone else in England's only innings, at the Basin Reserve, during a hefty innings loss (and he batted No. 11, below Simon Doull and Geoff Allott, which on reflection is a hoot).

A few days later he was asked to square the series in the final Test in Christchurch. Chasing 305, England won by four wickets. Of the 146.4 overs it took, Vettori wheeled through 57, more than double anyone else. It was a ludicrous load on slender shoulders.

So, being an integral part of New Zealand cricket is nothing new for Vettori.

New Zealand's finest cricketer? A matter of opinion, so no. Their most influential? Right up there.

David Leggat is chief cricket writer and chief sports reporter of the New Zealand Herald