Tactical Skill in Dodgeball
I have previously outlined how one can quantify the technical skill of players and teams using hit and defence percentages. I also showed that these skills account for about 75% of the points scored. What, then, determines the remaining 25%?
TAKE HOME MESSAGES
- Tactical Skill can be quantified by removing the effect of Technical Skill on point scoring
- Total Skill can be quantified and used to rank players in a team
What if everyone had equal technical skill
Recalling the plot from the previous post, there is a positive correlation between the weighted average for technical skill and the points scored per minute.
Data from the 5 games the Swedish Mixed Team played at EuroDodge 2018 in Lignano Sabbiadoro, Italy
The red line represents the expected point scoring for each level of technical skill. A player that has a technical skill of 27.5% is expected, on average, to score about -0.5points/min. This equates to getting eliminated once every two minutes without eliminating a single opponent, or getting eliminated on average after 30s and eliminating one opponent every second set. Given our opposition at the 2018 EuroDodge, one was required to have a technical skill of around 38% just to break even and contribute toward winning. The better the opponent, the lower the y-intercept is, leading to higher skill being necessary to score positively and win the game.
However, since there is some fluctuation in the data (the data points are not exactly on the line), there are additional factors that affect point scoring. One can quantify these additional factors by removing the effect that technical skill has. By calculating the distance of each point from the line, one is effectively rotating the entire plot and flattening the curve, so that everyone is on the same level of points/min with regard to their technical skill.
The black lines are called the residuals, and they correspond to these non-technical skills. The longer the line is above the red line, the greater the point scoring was above the expected, and vice versa below. Consider Male3 and Female2; the former was eliminated 5% less and eliminated 5% more opponents, but still managed to score some 0.7 points/min less. Clearly some other factors are at play.
Tactical skill
By calculating each player’s residual, and plotting them against points/min, we also get a positive relationship, although with a lower correlation (r = 0.47, as expected since 25% of point scoring is determined by this).
When excluding the technical skills from the point scoring, one is left with everything else that influences it. What that is is hard to determine right away, but it definitely includes aspects of decision-making and ability to read the game. The best name for this skill would be “Extraneous Skill”, but I’ve chosen to call this Tactical Skill.
Note that the tactical skill of Female2 is particularly high, since she scored a lot more points than expected given her technical skill. She did not have a particularly strong throw, or dodging ability. Instead she compensated by having magical hands, partly due to positioning on court, and partly due to great reflexes. This led her to make a lot of catches, inflating her point scoring above that of her hit and defence percentages. As is evident from the last two plots, catches mostly factor into tactical ability. This is because they are not accounted for in defensive skill. I’ve chosen not to include them there because they are relatively rare (compared with dodges and blocks), and their inclusion would obscure many of the other analyses due to the presence of positive points in defence.
We cannot be sure what is included in tactical skill, other than the fact that it does not include technical skill. In order to figure out what hides behind a quarter of your success as a Dodgeballer, one needs to identify other variables and compare them with the tactical skill score. If one identifies a positive correlation, but not for the technical skills, that means that the new variable taps into the Tactical skill-set.
To show that we indeed capture what determines success on court, one can calculate the Total Skill by taking the weighted average of technical and tactical skills (sum of technical * 3 and tactical divided by 4). Plotting Total Skill against point scoring shows that it almost entirely (96.3%) determines how many points an individual will score. The total skill can be used to rank players within a team.
One issue with tactical skill is that it is derived from the current team or lineup. For now, there is no way to calculate an absolute tactical skill, and one can only compare players within the same team. The best one can do is to normalise the tactical skill scores within the team, which will allow us to compare across lineups, and make additional conclusions regarding each player’s skill profile, such as whether technically or tactically dominant, which will indicate which skill-set the player should focus on developing during practice. Given the regression results, one can also determine which sort of training will yield the greatest benefit on court for each individual player, which will remove the guessing for the coaches, and bring optimal development toward winning games. I’ll follow up this post with one where I show how to create individual skill profiles.