V/AFL CHARTS

This page contains charts with minimal commentary about miscellaneous topics that have grabbed my attention along the way.

All of the charts can be clicked on to access a larger version.

AVERAGE POINTS PER TEAM PER GAME IN PORTIONS OF THE H&A SEASON

Data: Every Home & Away game from 2000 to 2017

Topic: Variability in average team scores for games played at different points in the Home & Away season

Points of Interest

  • Most common pattern is for scores to be higher in the early and late parts of the Home & Away season compared to the remainder
  • The most obvious exception was 2007

If we extend our view back to 1980, we see that the tendency is also evident across this longer timeframe.

EFFECT OF DAYS REST ON PERFORMANCE RELATIVE TO EXPECTATION

Data: Games from 2000 to 2017

Topic: Variability in teams' final game margins relative to expectation after having had varying levels of rest since the previous home and away season game

Points of Interest

  • For most teams, having less than 7 days' rest appears to have little to no effect on their performance relative to expectations
  • Geelong, the Kangaroos and Fremantle are the obvious exceptions
  • The Western Bulldogs and, to a lesser extent, Port Adelaide, appear to do relatively better on less rest

Note that some teams have, on average, over-performed (eg Hawthorn and Sydney) or under-performed (eg Gold Coast and GWS) relative to MoSSBODS expectations, so we should focus on the ordering of the dots for a team rather than the absolute values.

Never Before Seen Final Game Scores

Winning Score & Losing Score Pairing as Points

Data: Every game from 1897 to 2017

Topic: Proportion of final scores in a season (eg 72-67) that had never before been recorded in V/AFL history

Points of Interest

  • General decline in proportion of never-before seen scores starting from around the mid 1980s
  • Spike in late 1970s / early 1980s as higher-than-ever scores being recorded
  • Now about 1 game in 6 produces a record
  • 2017 produced the fewest never before seen scores of any season in history

 

Winning Score & Losing Score Pairing in G.B format

Data: Every game from 1897 to 2017

Topic: Proportion of final scores in a season (eg 10.12-9.13) that had never before been recorded in V/AFL history

Points of Interest

  • Similar decline in proportion of never-before seen scores
  • Similar Spike in late 1970s / early 1980s as higher-than-ever scores being recorded
  • Now about 65% of games produces a record

WINNING AND LOSING RATES IN CLOSE AND NON-CLOSE GAMES

Data: All games from 2000 to 2017

Topic: Evidence that some teams are better or worse at winning / losing close games relative to their overall winning rate across the period

Points of Interest

  • Adelaide and Sydney are the only teams for which the 2 SD confidence intervals do not overlap
  • Majority of teams have a closer to 50% record in close games than they have in other games
  • The size of the error bars on the Close Game bars (roughly) reflects the number of close games in which a team has been involved

TEAM FINAL SCORES THAT WERE PRIME NUMBERS

Proportion

Data: All games from 2000 to 2017

Topic: Extent to which teams' final scores were prime numbers

Points of Interest

  • Brisbane has registered a substantially smaller proportion of final scores that have been prime numbers, perhaps because of its spate of high scoring in the early 2000s (see this post for why that matters)
  • Lower-scoring teams such as GWS, Fremantle and the Western Bulldogs have registered a slightly larger-than-average proportion of final scores that have been prime (again, the blog post linked to above explains why these things are related)

Streak

Data: All games from 2000 to 2017

Topic: Number of consecutive games in which a team has avoided registering a final score that was or was not a prime number

Points of Interest

  • Brisbane and Geelong are the only teams to have recorded a streak of more than 40 games finishing on non-prime scores

Points of Interest

  • West Coast is the only team to have recorded five consecutive prime final scores
  • Hawthorn has never gone more that two games before recording a prime final score

All Teams' Winning and Losing Scores By Era

Data: All games from 1897 to 2017

Topic: Number of games during an era in which the final winning or losing score was prime or non-prime

Points of Interest

  • Winning scores are more likely than Losing scores to be prime, especially in more recent eras, partly because of the relative paucity of prime numbers amongst scores over 100
  • In the modern era, the most-common Losing Score has been prime (79 points), as have the second-most common (73 points), and the equal-third-most common (67 points)
  • Surprisingly, the most common Winning Score in the modern era is also prime (107 points), and was the case for the 1980 to 1999 era (113 points)

CHANGE IN TEAM CONVERSIOn RATES AFTER WINS AND LOSSES IN the home-and-away season

Data: All home-and-away games from 1997 to 2017 (excluding those for teams whose previous game ended as a draw).

Topic: How do teams' conversion rates tend to respond after a win and after a loss. Since teams that win tend to convert at slightly better-than-average rates and teams that lose tend to convert at slightly worse-than-average rates, one hypothesis would be that teams' conversion rates will regress towards the mean, falling after a win and increasing after a loss.

Note that conversion rate is defined as Goals / (Goals + Behinds).

Points of Interest

  • The hypothesis is very clearly borne out: in every season, winning teams tend to kick less accurately in their next game, while losing teams tend to kick more accurately
  • As well as being true for all of the seasons shown here, it in fact holds for all but a handul of seasons across the entirety of V/AFL history. In only 7 seasons have losing teams more often seen their conversion rate fall than increase, and in only 8 seasons have winning teams more often seen their conversion rate increase rather than fall.

TEAM WINNING RATE IN PREVIOUS 100 GAMES

Data: All games from 1897 to 2017

Topic: Teams' winning rate in 100 most-recent games, Home & Away and Finals, with draws counted as half-wins. Points are coloured based on a team's combined MoSSBODS Rating at the time.

Points of Interest

  • It's rare for a team to dip below 25% or rise above 75%
  • The generally cyclical nature of team performance levels across time is evident
  • Teams' ratings tend to rise fairly quickly when their winning rate is increasing (from whatever level) and fall fairly quickly when their winning rate is decreasing (from whatever level)

RELATIONSHIP BETWEEN SCORING AND WINNING RATE

Scoring Shots

Data: All games from 1897 to 2017

Topic: Relationship between Scoring Shot production and Winning Rate by Era

Points of Interest

  • Relationship is S-shaped for all eras, but steeper in some eras than in others
  • Fewer Scoring Shots are associated with a 50% win rate (about 25) in the 2000-2017 era than in the 1980-1999 era (about 28)
  • Increasing from 25 Scoring Shots to 29 Scoring Shots (ie just one Scoring Shot per quarter) in the 2000-2017 era is associated with about a 25% point increase in Winning Rate

Goals

Data: All games from 1897 to 2017

Topic: Relationship between Goals production and Winning Rate by Era

Points of Interest

  • Relationship is also S-shaped for all eras and steeper in some eras than in others
  • Fewer Goals are associated with a 50% win rate (about 13.5) in the 2000-2017 era than in the 1980-1999 era (a little over 14)
  • Increasing from 14 Goals to 16 Goals (ie just one Goal per half) in the 2000-2017 era is associated with about a 25% point increase in Winning Rate (from 55% to 78.5%)

Scoring Shots by Team (in Modern Era)

Data: All games from 2000 to 2017

Topic: Relationship between Scoring Shot production and Winning Rate by Team

Points of Interest

  • Only a handful of teams are able to win at a greater than 50% rate over a large number of games having registered only 24 Scoring Shots (Geelong, Hawthorn, North Melbourne, Port Adelaide, St Kilda, and Sydney).
  • Some register winning rates of over 60% with just 26 Scoring Shots (Adelaide, Fremantle, Geelong, Hawthorn, Melbourne, North Melbourne, and Sydney)
  • Carlton's winning rate goes above 50% only when it registers 29 Scoring Shots

RELATIONSHIP BETWEEN TOTAL SCORE AND VICTORY MARGIN BY ERA

Data: All games from 1897 to 2017

Topic: Relationship between the Total Score in a game and the Margin of Victory in that game

Points of Interest

  • In the modern era, higher Margins have been associated with slightly lower Total Scores than in the previous era. For example, the average Total Score for a Margin of 20 points has been 184.3 points in the modern era, whereas it was 187.7 points in the previous era.
  • If we consider games from the last three eras with a Total Score of 200 points, the expected Margins would be: 27.6 points for 1960-1979; 30.4 points for 1980-1999; 37.1 points for 2000-2016.

RELATIONSHIP BETWEEN EXPECTED DIFFICULTY OF PREVIOUS GAME AND PERFORMANCE IN CURRENT GAME RELATIVE TO EXPECTATION

Data: MoSSBODS-based expectations and actual game margins for all home and away games from 2000 to 2017

Topic: It's commonly asserted that teams benefit more from a 'tough' game than an 'easy one. We proxy game difficulty here by expected margin and assess performance relative to MoSSBODS expectation.

Points of Interest

  • No team shows substantial evidence of any relationship between its performance in one game relative to expectation and the difficulty of its previous game
  • The overall correlation is +0.008 (which is what zero looks like when it's putting on airs and graces)

CLOSE GAMES AND BLOWOUTS

Games Won by less than a Goal

Data: All game margins from home and away contests in 1897 to 2017

Topic: What proportion of games were "close", that is, decided by less than a goal

Points of Interest

  • In 2015 only 14 of 206 games finished with a margin under a goal
  • 2017 saw the highest proportion of close games since 1980
  • Close games were especially common in some of the early years of the competition and in the 1950s and 1960s
  • They were relatively rare in many of the seasons during the 1980s

Games Won by more than 5 Goals

Data: All game margins from home and away contests in 1897 to 2017

Topic: What proportion of games were "blowouts", that is, decided by more than 5 goals

Points of Interest

  • In 2015, 106 of 206 games finished with a margin over 5 goals
  • 2017 saw the lowest proportion of blowout games since 1998
  • Blowouts have been generally more common since about the early 1980s
  • They were relatively rare in the 1920s, 1950s and 1960s

DAYS SINCE WINNING AND LOSING SCORE COMBINATION LAST SEEN

Data: All winning and losing score combinations from 1897 to 2017

Topic: Depict how long it has been since every witnessed combination of winning and losing scores has occurred

Points of Interest

  • Most of the combinations of very low winning and losing scores haven't been seen for thousands of days, some since the first years of the V/AFL competition, which is over 40,000 days ago (or a bit over 4 in log base 10)
  • Darker colours are seen for scores that are more common in the modern era (and so have been seen more recently) although there are a surprising number of gaps even in that area representing scores that have never been witnessed