The 40/20

Other than the field goal, there are few more exciting kicking moments in rugby league than the correct execution of a 40/20. The 40/20, meaning that the kick is taken behind the player’s forty metre line, bounces in the field of play and goes into touch inside the opponent’s twenty metre, gives a huge advantage for the kicking team, as it advances the ball forty metres down the field and offers a fresh attacking set.

40-20.PNG

Introduced in 1997 for the Super League competition and retained for the NRL, the 40/20 doesn’t happen very often. You might see a successful attempt every five to ten games. Indeed, we see more field goals.

4020 fgs.PNG

Just as a bit of a trivial aside, Daly Cherry-Evans has kicked the most 40/20s in the NRL between 2013 and 2018, with sixteen, or one every 8.8 games he has started. The other players in double digits are Chris Sandow (14), Cooper Cronk (12), Cameron Smith (11) and Blake Green (10). Funnily enough, probable Immortal Johnathan Thurston never kicked a 40/20 in this period.

Embed from Getty Images

I don’t have the data to quantify the number of attempts made. Even identifying attempts would be a difficult exercise, as a skewed attempt can be easily disguised as a long kick downfieldNonetheless, the potential for a 40/20 is an interesting exercise in picking apart the mechanics of rugby league. The 40/20 has massive upside but it’s a low percentage play. The long kick is generally considered the safer option but what penalty do you pay for missing the 40/20?

Let’s set the scene. It’s not been a great set. The boys/girls got caught flat footed and returned the ball from the in-goal. A few one out hit-ups later and the team is at the forty metre line. It’s the fifth tackle (it doesn’t have to be but let’s assume it is). The play begins just over the forty, the ball is played, the hooker scoops it up and fires it off to the halfback. Decision time:

pird-banner-1.png

  1. Shoot for the moon and fire a long, low angled kick aiming for touch beyond the twenty, seeking to regain possession
  2. Put more power into the kick, at the expense of precision, and aim for some space between the fullback and wingers to drive the opposition as far back as possible
  3. Literally anything else

The options and their expected points are represented graphically here with our friend Cherry-Evans:

4020 dilemma.png

Let’s assume that option 3 fails. Even giving the ball to the likes of James Roberts or Latrell Mitchell and hoping something happens is a high risk play with plenty of downside. Having the centre fail to break the line or failing to sweep the winger around the outside, which happens far more often than not, means that you’re handing a set to your opposition on your forty-five.

This is our baseline, the worst possible outcome. We’ll measure the success or failure of each option in “expected points”. This is the expected value of the set, or an average of all outcomes, weighted by their probability. You might remember this from looking at short kick offs earlier in the year.

The opposition starting a set around forty metres out has about a 12% chance of that set ending in a try. A try is worth about 5.5 points on average (4 points plus the 75% league average conversion rate for the additional two points). The expectation is that this kind of set will, on average, generate about 0.66 points each time it is run. Given that the set in question is the opposition’s, the expected points are negative so -0.66 expected points are assigned to this option.

A successful 40/20 gives the kicking team possession on their opposition’s twenty metre line. From there, there is an 18% chance of scoring a try. This works out to +0.99 expected points, or nearly +1.75 to the better of the baseline worst case scenario.

An unsuccessful 40/20 attempt, but otherwise fine kick, would give the receiving team possession somewhere between their 20 and 25 metre lines. There’s about a 5% of chance of a try being scored from here, so that’s about -0.28 or 0.4 points better than the worst case outcome.

You’re looking at a success rate of around 25% to make the 40/20 worth going for. That is, the one successful kick will outweigh four unsuccessful attempts. If that ratio sounds familiar, it’s because it’s pretty close to the required success rate for the short kickoff and the short dropout to be worthwhile, which is a strange coincidence (or, stranger still, shows rugby league administrators have a good eye for balance).

pird-banner-2.png

There’s a massive “well, duh” incoming here. Of course going for the 40/20 and nailing it is a good thing. It’s rare because it’s really hard to do. You need the distance on the kick, the angle and, most importantly, the space available from the opposition’s placement of their outside backs. The best option is to take it early in the set when they are less likely to expect it.

There’s value to be considered in option 2, bashing the ball downfield. The conclusion is that kick metres are important. Not so much the stat in aggregate but the actual metres that the ball travels is important because it pushes the opposition back. A set that starts inside the fifteen will end in a try only 3% of the time. That equates to -0.16 expected points, which is still half a point better than doing nothing, but not that much better than the failed 40/20 attempt.

Unlike the other times I’ve looked at kicking strategy, there’s no clear cut answer here as to what is optimal. There are other factors at play, particularly defensive positioning, which means that situational awareness is paramount in the kicking player. The best advice I can offer is if you can go for it, go for it.

But I find this interesting because it explains part of why rugby league is played the way it is. Players don’t think in these terms but their behaviour can be understood using numbers to explain game play, bypassing players who tend to do their jobs very well but operate instinctively, not consciously.

Rugby league is a game defined by the battle for territory. Every ten metres is worth about 0.1 expected points. The trick is to convert the expectation into reality.