Just Take The Points!

Ever wondered at which point that it is profitable to kick for the corner rather than take the shot at goal? 

In our new section Just Take The Points! we aim to answer that very question. Through a combination of simple economic reason and data provided by the fantastic goalkickers.co.za, we can illustrate the good, the bad and the ugly coaching decisions week to week in New Zealand rugby.

The Situation

In a final act that sent social media into a frenzy, the Friday night clash between Taranaki and Tasman delivered up a doozy of a situation to open up JTTP. Tasman had the ball 22 out from the Taranaki line leading by six with time up on the clock. If they kick the ball out, the game is over, they walk away with four points and shoot to the top of the ITM premiership ladder.

This is where the beauty of the bonus point comes in. Tasman decided to have a crack at scoring a try – one that would gift them a fifth competition point for scoring four tries in the match. As you can see in the video below, everything went awry:

Tasman turned the ball over via a penalty for not releasing, Taranaki strung some phases together and eventually wing Waisake Naholo was able to part the tiring Tasman defence on the way to a try handy to the posts. When first five-eigth Marty McKenzie slotted the ensuing conversion, the humiliating loss was complete and Twitter subsequently blew up at Tasman’s perceived idiocy.

The Rationale

This is where conventional wisdom must go out the window. Here at JTTP, there is no such thing as a “win” or a “loss”, only competition points. The goal of every team is not to win as many games as possible, rather it is to maximise their competition points.

In this situation, the Makos of Tasman stood to gain one competition point by attempting to score a try and had a possible loss of three competition points should Taranaki be able to score a try and convert. By this logic, we can deduce that attempting to score a try rather than kick it out becomes profitable for Tasman when the likelihood of scoring is at least three times greater than the likelihood of a Taranaki converted try.

With the average conversion being rated as an 75.2% proposition per the ever-reliable goalkickers.co.za, we can re-write the profitability hurdle rate – the level where the expected value of competition points are equal – to be P(TRYTAS) > 3 * P(TRYTAR) * 0.752. In less nerdy terms, if Taranaki had a 1% chance of scoring a try, then Tasman should attempt to go for the bonus point if they have > 2.257% chance to score. This adjustment is huge, as in 24.8% of situations where Taranaki manage to pull off a miracle and score a try, Tasman can still be expected to escape with four points.

The Solution

This is where JTTP has to go away from numbers and attempt to take an educated guess at whether a team made the correct decision or not. Due to the shoddy (at best) stat-keeping of the ITM cup, we don’t have the data to tell you how likely a try is in each situation.

My best guess in this particular scenario would be that Tasman actually made the correct decision. 

With the ball just 22m away from the Taranaki line, perfect conditions for running rugby and being a high powered offence against a team that had already given up 30 points, the situation couldn’t have been much better for the Mako men. Factoring in that Marty McKenzie is hardly the next Johnny Wilkinson in terms of goal kicking and the Tasman decision has sound statistical backing.

Sadly however, in this country the results almost always outweigh the process. In a sport that is so deeply seeded in conventional thinking and cliché, this decision will be torn to shreds around the country – with even the Mako captain himself ripping on the thought process in the post-match interview.

This situation was not where you should just take the points.