Fitness levels that would eclipse most All Blacks is one reason why Trent Boult can become a genuinely world class cricketer says New Zealand coach Mike Hesson.

Left-arm seamer Boult’s 10-wicket haul in New Zealand’s innings rout of the West Indies in Wellington was 12 months in the making, according to Hesson.

He says the 24-year-old’s second-Test display at the Basin Reserve was nothing out of the ordinary in a calender year that has seen him claim 41 Test scalps.

With one Test to play in 2013, starting against the West Indies in Hamilton on Thursday, Boult is already among the most prolific Black Caps bowlers in any calendar year.

Above him are Sir Richard Hadlee (64 wickets in 1985), Daniel Vettori (54 in 2008) and Chris Cairns (47 in 1999).

“Trent’s been bowling well for over a year now,” Hesson said.

“Yet he hasn’t got the wickets that he probably deserves and other people have done that.”

Hesson says Boult’s presentation of the seam is bettered by no current Test bowler, allowing him to generate late swing – the weapon that top-order batsmen fear most.

He has also increased his speed, meaning a feisty bouncer is in the arsenal to push opponents onto the back foot.

A key to all these improvements is a focus on fitness.

Aerobically, Boult’s results on the “yo-yo” running endurance test are routinely compared with other top New Zealand sportsmen – including the fittest rugby players.

Hesson says the outcome reflects “very favourably” on the lean Boult, which explains why he can produce up to four quality spells on any given day’s play, with little drop in standard.

Hesson says Boult’s friendship and rivalry with fellow-new ball bowler Tim Southee, 25, also acts as a spur.

The Northern Districts swing specialists are both young enough to forge long and successful careers at the top level, Hesson believes.

Following their three-day win, Hesson granted his players the weekend off before they reconvene in Hamilton on Monday.

That wasn’t the case for the West Indies after their harrowing innings and 73-run defeat.

They endured a lengthy net session at the Basin Reserve on Saturday, with promises from the coaching staff of more of the same over coming days.