He runs in and hits the deck hard at a short-pitched length. It's an effort ball that gets up into the batsman's ribcage. While the pace - mid-130s kph - isn't disconcerting, the bounce is. He does it again the next ball and the ball after that. There's more of the same in his next over. And he bowls an almost identical set of deliveries for the next six or seven overs.

Meet Neil Wagner, the No. 2 Test bowler in the world. He has taken over 200 wickets in under 50 Tests and has bounced out the best in the business, including Virat Kohli and Steven Smith, in different conditions. Nearly two out of every three of his Test wickets come off deliveries that are short - a lot of them bouncers.

While his fast-bowling team-mates, Trent Boult and Tim Southee, are release-swing bowlers who look to keep the ball in the air longer, pitching it fuller to give it more time to move (which is what the greenish New Zealand pitches call for) Wagner has carved out his own niche and is hugely successful in his craft. Boult and Southee are your quintessential swing bowlers, and so they take the new ball.

While New Zealand's pitches usually have a fair amount of green grass on them, the surfaces underneath aren't always rock-solid, and so the tracks are somewhat slow. (The pitch in Christchurch for the second Test against India was an aberration; Kane Williamson referred to it as an Australian pitch.) On these slowish surfaces, the fuller you bowl, the more you trouble the batsman. The swing in the air is accentuated by the lateral movement you get off the deck, because of the softness of the surface and the grass cover.

Wagner, though, uses this softness in unique fashion. Negotiating a bouncer on a slow surface is a challenge. It might sound counterintuitive but the last thing you want as a batsman while facing a bouncer is time. Negotiating a fast bouncer on a quick pitch is easier, for it comes and goes in a flash. Once you've made up your mind to either attack or defend, you go through with it without entertaining second thoughts. But that's not the case with a mid-130s kph bouncer, particularly one on a slower surface. Invariably the relative lack of pace makes you think twice.

Wagner bowls a barrage of short deliveries from different angles, while sticking to the sort of height that lets him get away without being notified for having bowled two bouncers in the first four balls.

He is relentless in his plan and execution, which makes it easy for the captain to set a field that supports the strategy.

He has proved time and again that it's nearly impossible to hit your way out of a bouncer trap. When you start taking him on, you play straight into his hands: with as many as four fielders (fine leg, square leg, third man and deep point) positioned for the eventuality, it's only a matter of when (and not if) you hole out in the deep. Only once in a while does he bowl a delivery that can be played off the front foot, and even then it's a knuckleball, a yorker, or an attempt to pitch it really full trying to get the batsman bowled or lbw.

Most fast bowlers develop a line and length that allows them to operate at about 70% in most spells, but with Wagner it seems like every ball is bowled with 100% intensity. And he bowls really long spells without dropping that intensity, which is not the norm for such bowlers.

All this explains why he picks up so many wickets and why he is Williamson's go-to bowler once the ball gets old, the pitch is flat, and the opposition are on top. It isn't easy to find a workhorse like Wagner who isn't defensive and yet provides control and makes things happen in modern cricket.

What does all that tell you about batsmanship? The fact that on average two out of three Wagner dismissals come off short-pitched deliveries reflects poorly on how batsmen are handling the barrage of bouncers. It also perhaps raises the question of why more bowlers aren't following in Wagner's footsteps.

Facing the bouncer can be both scary and intimidating, but if a batsman decides to play it defensively, there's little a bowler can do to dismiss him. The likes of Steve Waugh and Virender Sehwag weren't good players of the short-pitched stuff overall, but were committed to their defensive plans against bouncers that came their way. If you decide that you're going to only duck, sway away or ride the bounce, the only way of getting dismissed is if the ball gets too big on you while you're attempting to ride the bounce. There really is no other way to dismiss a batsman when the ball is above the waist and a shot is not offered. You may get hit, but then, whatever doesn't get you out doesn't hurt as much.

In his partnership with Ajinkya Rahane in the second innings in Christchurch, Pujara offered a good example of how such an approach affects the bowler. He believed in his defensive game and kept leaving the bouncer or riding the bounce. He was a little uncomfortable once in a while (which is par for the course) but did not deviate from his plan. As a result he got deliveries of a length he could drive from Wagner - who bowled only bouncers to Rahane at the other end.

The benefit of not engaging with the short ball is that, sooner or later, the bowler, even if his name is Neil Wagner, gets bored or frustrated or both and is forced to try something else. Rahane just couldn't make up his mind about his plans. He tried to hit his way out of the bouncer trap, but after the first couple of attempts, realised the futility of his approach. He then tried to duck or sway but wasn't fully committed to that either. In the end he was dismissed off a ball that was short but slow and hardly bounced; he dragged it onto his stumps to finish perhaps the ugliest Test innings of his career.

We all know that Rahane is a much better player than he was that day, but that innings told us things about a lot of modern batsmen. A lot of them are strokeplayers by nature, and they play that way in red-ball cricket too. While that works out fine in favourable conditions, not many have the answers to a relentless Wagner-like bouncer barrage.

The fact that there's a Boult or a Southee at the other end asking probing questions makes Wagner even more effective. There's simply no breathing space when the ball is swinging from one end and is at your throat constantly from the other. In Wagner, New Zealand have found a perfect all-weather bowler who compliments their existing stocks.

Aakash Chopra is the author of three books, the latest of which is The Insider: Decoding the craft of cricket. @cricketaakash