Beauden Barrett's struggles off the tee have been laid bare by some in depth goalkicking statistics.

All Blacks star Beauden Barrett has been rated the worst goalkicker in international rugby in the past five years.

While it's no secret the talented playmaker has had his troubles off the tee, statistics now reveal just how bad he has been, with the two-time World Rugby Player of the Year (2016 and 2017) ranking dead last of the 52 kickers ranked.

There has traditionally been no easy way to compare goalkickers aside from pure shot-at-goal percentages, but thanks to the methods of South African website goalkickers.co.za, more factors can be considered.

PHIL WALTER/GETTY IMAGES Beauden Barrett takes to some solo training during the coronavirus lockdown.

Their devised algorithm takes into account the difficulty of a kicker's attempt at goal and the difficulty of each kick is given a rating (10 being the highest).

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Factors considered to establish the difficulty rating include: distance of the kick, angle of the kick, altitude, side of the field and foot used, score difference (to indicate pressure), home/away and first half/second half.

The difficulty rating then produces a 'value added' statistic, which shows how many points a player scored more than he would be expected to - relative to other professional goalkickers.

ANDY JACKSON/STUFF A 'value added' rating of -16 in tournament play over the past five years essentially means Beauden Barrett has cost the All Blacks 16 points with his goalkicking.

The higher the kicker's 'value added', the better the performance. It also works in reverse, with a negative score meaning a player had missed kicks they really should have slotted.

Statistics gathered by goalkickers.co.za include just competition test rugby since the start of 2015, so that's two World Cups, five years of the Rugby Championship and six editions of the Six Nations.

And, with WalesOnline having collated the overall numbers, Barrett is bottom of the heap, when listed by the most crucial 'value added' score.

STU FORSTER/GETTY IMAGES Richie Mo'unga has taken over the goalkicking duties in his two years on the international scene.

The 28-year-old has kicked 83 out of 118 in those competition matches in that time, for an average of 70 per cent, with his 'value added' being -16 - essentially meaning his work off the tee has actually cost the All Blacks 16 points.

The 83-test first five-eighth-cum-fullback has mostly relinquished the goalkicking duties to Richie Mo'unga in the last two years, and the Crusaders pivot makes the top half of the rankings, coming in at 23rd spot, according to WalesOnline.

Mo'unga has kicked 39/48 for 81 per cent, with a 'value added' of 1.

LAURENCE GRIFFITHS/GETTY IMAGES Wales fullback Leigh Halfpenny is rated top of the pops in the goalkicking department.

Topping the overall charts is Wales fullback Leigh Halfpenny, who has kicked 87 per cent and has a 'value added' of 30.

Fellow Welsh sharpshooter Dan Biggar has slotted 89 per cent, however the first-five's 'value added' is 24.

Scotland's Greig Laidlaw rounds out the top three (84 per cent and a 'value added' of 22) ahead of England's Owen Farrell (79 per cent, VA19).

The top southern hemisphere goalkicker comes in at No 5 and is Argentina's Nicolas Sanchez (84 per cent, VA15).

Dan Carter is the top Kiwi on the list, at No 11, (76 per cent, VA5), with 2015 having been his last year in test rugby.

Meanwhile, goalkickers.co.za also has statistics for the past five years of the world's top domestic competitions.

In Super Rugby, Barrett ranks second-to-last, at 88th, with 72 per cent and VA-29.

But, remarkably, the man below him at the bottom of the charts is in fact Mo'unga, with 74 per cent and VA-37.

Top of the Super Rugby numbers is former Bulls (now at Montpellier) first-five Handre Pollard, with 81 per cent and VA48.

AT A GLANCE

The top goalkickers

1. Leigh Halfpenny (Wales), 87%, VA30

2. Dan Biggar (Wales), 89%, VA24

3. Greig Laidlaw (Scotland), 84%, VA22

4. Owen Farrell (England), 79%, VA19

5. Nicolas Sanchez (Argentina), 84%, VA15

Also:

11. Dan Carter (New Zealand), 76%, VA5

23. Richie Mo'unga (New Zealand), 81%, VA1

52. Beauden Barrett (New Zealand), 70%, VA-16