Rugby is a traditional sport – not a whole lot changes very often.

In fact, it was with some furor that for last years' World Cup, Australia changed their selection rules to allow some of their greatest exports to be again selected for their country despite playing overseas.

However, it is hard to argue with results, and the Australians finished a close second to the All Blacks in the Final.

But not all nations are as open-minded as the Aussies, with rugby hotbeds New Zealand and England still disallowing national representation if you play outside their shores.

Let's have a look at some potentially great international careers we lost due to eligibility rules.

Steffon Armitage

International caps: 5

Unfortunately for England, Steffon Armitage's rugby career took off like a rocket after moving to France and joining Toulon.

Even more unfortunately for the RFU, Armitage is exactly the kind of player the English could've used over the past few years.

The recipient of the 2014 European Player of the Year award is known for strength, speed and his ability to win turnover ball at the ruck, as well as his versatility (he can play either as an openside or an eighthman).

At age 30 with only 5 caps to his a name, who knows how good a contributor he could've been for his nation, especially at World Cup time.

Ben Mowen

International caps: 15

Ben Mowen is so far the only international captain to put himself in this position.

At the time of his departure, he had just taken over the Wallabies skipper role from James Horwill, but shortly after left to France with his wife and daughter in mind.

It is an admirable move from Mowen – whilst living in France on $700,000 a year is hardly a kick in the nads, he gave away his opportunity to lead the green and gold into a World Cup to assure his young families' future.

If he had stayed, Australia would likely be able to field two or three international back rows right now with their depth.

Charles Piutau

International caps: 16

Charles Piutau was another who began to show promise just as he signed on to move overseas. 16 caps in three seasons for the All Blacks were apparently not enough for the young fullback, and he was off to Europe.

Since then, in his time with Wasps and Ulster, he has shown he has the ability to be a game-changing fullback, turning in good performances in local footy as well as the European Cup.

Naturally, this will not faze the NZRU, who are known to have the best player depth of any nation in the world. But will it faze Piutau knowing that he may now be a World Cup champion had he stayed in New Zealand.

Regan King

International caps: 1

Making his international debut in 2002 after only 11 games at Super Rugby level, Regan King was earmarked as the eventual successor to Tana Umaga's 13 jersey.

King unfortunately lost his World Cup shot in 2003 due to injury, as well as most of 2004, and at the end of the year he took up a lucrative contract with Stade Francais.

In 2006, online publication Planet Rugby voted King as the best outside centre in the world. He was the only player in the “World XV” who had not played international rugby that year.

One year later, the All Blacks exited the Rugby World Cup at the hands of hosts France at the quarterfinal stage. How they would've loved to have deployed King in the 13 jersey at that tournament.

Nick Evans

International caps: 16

Nick Evans made his international debut for the All Blacks in 2004, impressing even from his first hit-up of the ball in test footy. Naturally, he made the 2007 World Cup squad, where he continued to impress at both five-eighth and fullback.

All it took for Evans to be convinced he would be better off overseas was being overlooked for the Tri-Nations series in 2008. He moved to England shortly after.

Since moving to the Harlequins club in London, Evans has made 188 appearances, scored over 2,000 points, and has won two trophies both domestically and in Europe.

Such a great footballer is Evans you'd almost think the NZRU, even with their depth, would take him back if they had the chance.