Offspinner William Somerville had barely been heard of on the international circuit before he took seven wickets in the deciding Test of one of 2018's most remarkable series. He's also been barely heard of since.

This is no slight on him. He dismissed some of Pakistan's best batsmen and was a genuinely key player in New Zealand's victory. But his story so far is the result of two trends. First, while New Zealand have had excellent fast-bowling depth for several years, their spin stocks have recently started to look healthy too - Ajaz Patel, Todd Astle and Mitchell Santner are all in the mix. Second, as teams become more unashamed about preparing home tracks that maximise their strengths, Somerville could be part of a growing group of Test bowlers who are essentially overseas specialists - players who make the XI and produce vital performances in conditions that suit them, and yet are not considered for a place at home. Kasun Rajitha, Sri Lanka's 26-year-old seam bowler, is another example of this species of player.

After that win in Abu Dhabi, New Zealand played two home series, against Sri Lanka and Bangladesh. With two Asian teams touring, seaming decks were always going to be prepared. Somerville was not needed for either squad.

"I wasn't expecting to play the home Tests," Somerville said in Galle, ahead of the first Test against Sri Lanka. "Ajaz has taken the most wickets in home conditions in New Zealand for the last three domestic seasons. But I was very, very grateful to be a part of that win against Pakistan away, for the first time in 1969."

Somerville realised that the next tour of Asia represented his best opportunity. Where New Zealand almost never field three frontline spinners in a Test - the Sharjah Test in 2014 being the last occasion - they appear likely to do so at Galle, which, on reputation, is the most spin-friendly venue in the world. Somerville is one of four spinners vying for one of those places, but as the only one of those spinners whose stock ball turns away from the left-hander, New Zealand are likely to pick him.

"I've had my eye on this tour," Somerville said. "I spoke to [coach] Gary Stead at the end of the New Zealand domestic summer and said, 'I want to be able to bowl on grass in New Zealand in preparation for touring Sri Lanka.' So I went and joined the winter squad in Lincoln, where they have a marquee. It's the middle of winter and five degrees, but you're indoors, bowling on grass. I've got myself ready for this tour, and it's nice to be here and be selected."

Somerville doesn't personally count himself unlucky to have been overlooked for the home series, despite his outstanding debut. In fact, only eight months before that Abu Dhabi Test, he was playing second XI cricket for New South Wales. Unable to gain a regular place in the New South Wales first-class team because Nathan Lyon and Steve O' Keefe played for the same state, he moved back to his native New Zealand last year, and was surprised to be called up to the Test squad after only two first-class games for Auckland.

"I didn't even know I was on the radar, for New Zealand," Somerville said. "I assumed it would take one or two seasons. It was a lot faster than I was expecting. But Todd Astle got injured, and I got the call as a replacement for him."

Somerville would, of course, be ecstatic to eventually play a home Test for New Zealand, but for now, the intensely spin-friendly nature of Sri Lankan surfaces may give him another Test-match opportunity, even with Astle and the other New Zealand spinners all fit. Sri Lanka have players of their own who are essentially away-series specialists - Rajitha most prominent among them. Rajitha has played all six of his Tests away, and despite having contributed outstanding spells in Test wins in Barbados and Port Elizabeth, he cannot claim a place in this home Sri Lanka squad either.

With South Africa, New Zealand, West Indies and each of the South Asian sides all now overtly intent on preparing tracks to suit the home side, Test journeys like Somerville's could become more common.

Andrew Fidel Fernando is ESPNcricinfo's Sri Lanka correspondent. @afidelf