How do the numbers add up for boot boys?
of the kicks? First of all, it’s best to explain what contributes to rating the difficulty of any given kick.
The difficulty of a kick is based on the following factors - which must have been proved based on past data and using the right statistical techniques:
■■ distance of the kick
■■ angle of the kick
■■ altitude
■■ side of field and foot used
■■ score difference (to indicate pressure)
■■ home/away
■■ 1st half/2nd half
The website cites that, based on past goal kick data, distance and angle carry by far the most weight and are the two variables used in our current model. So, for example, a kick right in front of the posts, with little angle or distance, might carry a probability of success rating not far below 100%.
But a kick right on the touchline could have a rating of around 40% or even less.The average difficulty of the kicks are then converted into a score out of 10. The higher the score, the more difficult the kicks.
Halfpenny’s average difficulty was 4.9, while Biggar’s was 3.7 - meaning Halfpenny had tended to take on trickier kicks.
That’s hardly a trade secret - given that the full-back has tended to take care of the longer shots at goal.
But the final piece of number crunching that proves their worth is working out the value they’ve added to the team through goal-kicking.
The value added statistic measures the number of points the kicker scored more than he would be expected to given the difficulty of his kicks – relative to other professional goal-kickers.
And, again, it’s Halfpenny who comes out on top in this one.
The full-back has added 30 points more than was expected of him based on the difficulty of his kicks, while Biggar has added 24 points.
So, there you go.
It’s not exactly clear cut but, factoring it all in, this system suggests Halfpenny has just about been the more valuable in recent years.