Every so often, a player comes along who looks as if their talents will help them write themselves into the rugby history books for both club and country.

Sometimes we're right, sometimes we're wrong, and sometimes we're wrong when we absolutely should've been right.

Here are six players who possessed all-time talent but for one reason or another did not fulfill it.

Note: Players who rendered themselves unavailable for their country through playing overseas will not be included in this list.

James Hook

It's hard to label a man with 81 caps for Wales and fourth on their all-time points scoring list an unfulfilled talent, but considering the natural gifts Hook possessed, most Welsh rugby fans would agree with this selection.

A fantastic passer with great tactical awareness and a reliable kicking boot, Hook also possessed game-breaking running skills which saw him draw comparisons to Welsh legend Barry John and even Dan Carter.

Unfortunately, his versatility and vast array of skills saw him confined to a utility role rather than a proper position within the Welsh lineup. Had he been employed at 10 his entire career, we could've bore witness to the birth of another great Welsh five-eighth.

James O'Connor
Again, at age 25 it is tough to definitively label O'Connor with anything, but from the youngest Super Rugby and second-youngest Wallaby debutant of all-time, Australian rugby has every right to feel cheated by O'Connor.

Whilst also suffering from the “utility” tag the man above him was labeled with, O'Connor's ill-fated move from the Western Force to the Melbourne Rebels was a disaster, with the temptations of a big city fuelling his self-destructive lifestyle.

The final straw saw him removed from Perth Airport by the Australian Federal Police, which saw his ARU contract torn up and prompted a move overseas. Sadly, it is unlikely we will ever see him in Wallaby gold again.

Gavin Henson

Both fans and rugby legends alike have suggested on numerous occasions that Gavin Henson was “the most talented back Wales have ever produced”. Why is it then that in the 10 years he was in the Welsh fold he was only capped 33 times?

Like so many professional athletes, particularly those from small towns, a taste of fame and the big city proved too much for Henson, and rugby started to play second fiddle in the lifestyle he started to lead.

Henson became known less for his rugby and more for his reality tv “career” and high-profile celebrity relationships. Sadly for Welsh rugby, Henson never even appeared at a World Cup.

Quade Cooper

Quade Cooper is one of the more mentally stable players on this list, and has not wasted any of his talent in the traditional sense of the phrase.

Rather, Cooper's ill-fated inability to improve on the weaknesses in his game have seen him not rise to the heights that the all-worldly talented first five may have.

With a penchant for passing without thinking, attempting far too ambitious maneuvers and failing to find the balance between his own attacking flair and providing for his team-mates, Cooper will forever be known as a style over substance player, useful only for YouTube purposes.

Rupeni Caucaunibuca

Without wishing to completely assassinate the character of a man who is by all reports a fantastic human being, some players are just so undeserving of their talent you'd rather they didn't have it.

Constantly late and even a no-show for training, for flights and for games, Caucaunibuca lost the trust of just about every team and team-mate he played with, despite being labeled as maybe the “world's best player” by internationals Chris Paterson and Mike Tindall.

Despite aspirations to appear at the 2016 Olympic Games for Fiji in the sevens format of the sport, his rapidly expanding waistline is rapidly making sure that will not be a possibility.

Mark Ella

To go on about the greatness of Mark Ella would take far too long – many of Australia's most prominent Wallabies list Ella as the great fly half the country has ever produced.

Those who knew Ella best, such as David Campese, Roger Gould, Michael Hawker, Simon Poidevin, dual international Michael O'Connor and even rugby league great Wally Lewis list Ella as the greatest player of all-time – in either code.

In 1984, aged just 25, Ella retired from rugby, stating that he had “other things” to achieve in life.