AFL Rankings: Round 8 2020

St. Kilda’s improvement this season has been fuelled by its goal accuracy. Have the Saints been better or lucky?

The Saints come marching back

St. Kilda’s impressive win against Port Adelaide at Adelaide Oval in Round 8 moved it up to third on the AFL ladder. So far, this is looking like a significant improvement on last year’s fourteenth-placed finish, and the sixteenth-placed finish the year before that.

On the rankings, the Saints have gained more ranking points this year of any team except the Gold Coast Suns. The Saints have an average net margin this year adjusted for home ground advantage and opponent strength of +12 points (see chart below). This has been driven by impressive wins against Port, Richmond, and the Western Bulldogs. In their last 14 matches for 2019, their average adjusted net margin – also deflated to compare with this year’s shorter quarters – was -16 points.

St. Kilda has scored more points than any team so far this season besides Brisbane. However, in terms of scoring shots per game this year it only ranks tenth. Have the Saints actually improved by as much as the results suggest, or have they got a bit lucky? Or like Tim Membrey’s scissor-kick goal – is it perhaps a bit of both?

St. Kilda suddenly becomes deadly accurate

In recent years, the Saints have been somewhat let down by their inaccuracy when kicking for goal. So far this year, they have been amazingly accurate.

St. Kilda kicked 12 goals and one behind against Port Adelaide, making it the first team in the VFL or AFL in 120 years to win a match when scoring only one behind. Against Richmond in Round 4 the Saints kicked 15.3. Against the Bulldogs in Round 2 they kicked 14.4. That means in their three most impressive wins this season they scored 41.8, meaning they scored at an astonishing and seemingly unsustainable conversion rate of 83 per cent.

The Saints have generated good shots

Many AFL followers with at least a passing interest in more advanced AFL statistics would know of the concept of expected score, which is the score a team would be expected to kick given the location of their shots on goal. A really good resource for this is Stats Insider’s Shot Charting Explorer. This can help us work out if the Saints have been accurate in front of goal because they have been generating good shots, or because they have been converting those shots into goals at better rates than you would expect?

According to Stats Insider’s data, it is more the former. St. Kilda expected score this year given where they have taken their shots at goal from is higher than its actual score. The Saints’ actual scores were only slightly higher than their expected scores in their wins against the Tigers and the Bulldogs. They have still substantially improved their shot-taking from last year, but it is their shot-creating that has been really good.

Up to Round 7 the Saints had taken around 30 per cent of their shots at goal from zero to 24 metres out this year according to the Stats Inside figures, up from around 20 per cent last year (see table below). Less of their shots have come from the 25-49 metres range. Their accuracy is up by at least 10 percentage points from both the below 25 metres range, and the above 50 metres range.

Furthermore, the Stats Insider’s heat maps (see below) show that more of their shots have come from directly in front of goal rather than to the left or right, which is probably why their accuracy has improved. Last year’s heat map is fairly typical of most clubs in its spread around the 50 metre arc. This year’s heat map, once it gets near the goal mouth, is arrow-straight.

Straight shooting Jack

One player who is emblematic of the Saints’ improved goal accuracy is Jack Billings. In 2018, Billings kicked 14 goals and 19 behinds. In 2017 he kicked 23 goals and 36 behinds. West Coast’s Josh Kennedy kicked only three more behinds, and bagged 46 more goals. If Billings had been able to convert at the league average, then he would have added 1 or 2 more points per game to the Saints’ score – small in the context of the overall result, but a sizable proportion of the contribution of one player.

This year Billings has kicked seven goals and just one behind. His actual score of 43 has been 15 points higher than his expected score, according to Stats Insider. In contrast, he scored five goals less than his expected score in 2018, scoring a goal on about one-quarter of his shots from 25 metres or more.

A fair proportion of goal accuracy is random: one year’s straight shooter can be next year’s sprayer – even if you are Ben Brown. If the Saints can keep generating shots as good as they have though, they are on a fairly sustainable path.