Tim Southee, Trent Boult, Doug Bracewell - 23, 23 and 22 years old, respectively, have led New Zealand's fast bowling group to a first Test win in Sri Lanka for 14 years.

How have New Zealand gone from a "wizened and geriatric" bowling attack (Chris Martin, Shane Bond, Daryl Tuffey and myself) at the very end of 2009 to one so fresh-faced and young?

A more important question is why? Why is the New Zealand attack so young? But the most important question is: where are New Zealand's 28-32-year-old quick bowlers? The bowlers in their prime, the bowlers at full growth, strength and ability.

The simple answer is that most of those bowlers in the 28-32 age bracket aren't there playing in New Zealand. There is a strange hole in the fast-bowling cupboard. A hole that was created by a system that was supposed to keep the cupboard well stocked. The New Zealand academy. But this is not an article calling out the academy; rather a look at why this happened.

The academy took the best young players in the country and, for the winter, based them in Lincoln, Christchurch. The reward was coaching, an end-of-winter tour, and an opportunity to eat, sleep and breathe cricket for the off-season.

That all sounds great to a youngster. The issue was - and the system has now changed considerably - that all the bowlers who were sent to the academy were, in essence, turned into clones. Bowling actions were not just tweaked, they were thrown out and a complete remodelling process was started.

This "cloned" action was one based mostly on biomechanics. It was seen that this action was the most economical from an energy-output-to-pace-attained perspective. This action was seen to be the safest in relation to injury prevention. It was also seen to be the best from a technical point of view, as it allowed bowlers to swing it both ways with a similar action.

Where is the dotted line? Sign me up. This all sounds amazing. An action that won't cost me as much energy, I'd be injured less and I'd be able to swing it both ways. Too good to be true? Unfortunately it was. And for a while, New Zealand have been paying the price.

The "academy action" was implemented for all the right reasons. The statistics and the proof were there to back this programme.

But how many international bowlers have the same action? How many are clones of each other? Fast bowlers, just like their lazy spinner friends, are instantly recognisable by the often quite drastic differences and quirks in bowling actions - part of the beauty of our wonderful game.

It now seems that the decision, at 25, after my first season of first-class cricket, to turn down an opportunity to go to the academy was one of the better ones I have made

We don't often muddle up bowlers when we just glance up at one of them running in, because of these differences. Each bowler is different. And each bowler's body is different. Every body on this planet is different. Whether it be muscle size, limb length, or level of flexibility. We are all different. So how can we expect there to be one action to suit all types?

Making changes to reduce the risk of injury is commonplace. Usually this is done on the back of having an injury during the rehab process. I hate hearing this as often as I do.

A bowler's body has become used to doing what it does since he first let go of a ball. Take a fresh, fit 18-year-old; maybe been playing cricket since he was six and just starting out on a first-class career. He has been bowling in preparation for 12 years. His maturing body has become strong in the places in which it needs to be strong. Twelve years of associated functional strength work from bowling.

This build-up lends itself to only making tweaks to an action. Changes can, and often will, cause injury because you have made a change that a body isn't strong enough to endure, and the body doesn't have the 12 years of strength to rely upon to absorb the new forces and impacts.

Tweaks, not changes. Tweaks lead to changes, but slowly. And slowly is safely. Wholesale changes - remodelling - more than often will lead to serious injury, often stress fractures, because the body is just not used to this new action and can't absorb the new forces.

To draw an easy analogy, take muscle soreness after running for the first time in a few months. For a day or two after, we can be very sore. This is because the body isn't used to these activities. For a bowler doing something new, add in the straight line and rotational forces, the torque, the stresses, the sudden jarring and repetitive impacts, and then add up the amount of time a bowler has had to become strong in his action to be able to do this day in day out. How long will it take to make a change and then be strong enough to continue with the change before serious injury occurs?

There will be a phase where the body can absorb big changes and things can go along smoothly. Just ask three bowlers who could and should have gone on to more - Richard Sherlock, Te Ahu Davis and Taraia Robin. All remodelled by the academy, all had success, and then all came down with similar injuries within a year of each other. Three bowlers who were naturally quick, and whom New Zealand have missed out on.

It now seems that the decision, at 25, after my first season of first-class cricket, to turn down an opportunity to go to the academy was one of the better ones I have made. My action is my action. My coach was always tweaking it, I was always tweaking it, and all bowlers will make tweaks as the days, and years, go by. Tweaks are fine. Tweaks can lead to changes, but by making tweaks it is a slowly, slowly approach. The body can then adapt and become used to the new movements. Too big a change or too much time off leaves the foundations weaker and opens the door for injury.

Fast bowler Iain O'Brien played 22 Tests for New Zealand in the second half of the 2000s