The rates of pass attempts and defensive actions (excluding recoveries and fouls) may be used to effectively discriminate player on-field roles. We have used the "Role Chart" biplot for a couple different purposes recently - to test Brad Evans' adaptation to the centerback position and evaluate Micheal Azira's temporary adoption of Osvaldo Alonso's on-field responsibilities. Shown above, the 2014 numbers for 11 players selected from each MLS team (all data collected from whoscored.com) illustrates the same message: nominal role defines stat accumulation. But that isn't the only information in the scatterplot. Average pass attempts and defensive actions also vary by style of play, and the distribution of roles by team can give us some hints concerning tactical approach.
In 2014, the Houston Dynamo recorded fewer possessions per game - and passes fewer times while retaining possession - than the Seattle Sounders. That Seattle starters, on average, recorded more passes per 90' should not, therefore, be a surprise. If, instead, we normalize both axes to team context (as shown on the right) we remove some of this pace-dependent information and may perceive how Seattle relies on specific roles in comparison to other teams. I find it helpful to mark the 10% lines for both axes (dashed line), showing where actions, if distributed evenly, would fall for all outfield players (if, in an ideal world, a goalkeeper does absolutely nothing). Summarizing some observations from the plots:
- In 2014, passing numbers were broadly distributed across all starters.
- Centerbacks received a distinctly high proportion of defensive actions.
- Fullbacks exhibited, on average, similar passing and defensive responsibilities to midfield players.
More gifs please
Owen Coyle's 2015 squad has changed several of these patterns... but shifting lineups and personnel have not yet revealed - in the first 5 games - exactly what the Dynamo average performance will look like. Suffice it to say: in game 5 vs. Seattle, centerback Jermaine Taylor had the largest share of basic passes (13.9%) and by far the largest share of defensive actions (23.6%, 7% above DaMarcus Beasley) on the team... and that probably isn't the sign of a team that should expect 3 points.
- A very high distributional load was placed on the midfield trio of Osvaldo Alonso, Gonzalo Pineda, and Marco Pappa.
- Alonso joined the 4-man backline in exhibiting >10% defensive shares.
- Clint Dempsey and Obafemi Martins had higher-than-average passing loads for MLS forwards (even with normalized data), and similar distributional load to the fullbacks.
- As I've mentioned before - Lamar Neagle defended like a midfielder and distributed like a striker.
How have things changed in 2015?
Seattle hasn't had a "normal" performance yet in 2015 (as should probably be expected from 3 games involving red cards, and 1 game played without 5 starters), but game 4 showed promise in this regard. Alonso and Pineda were back in their 2014 territory. Chad Marshall and Brad Evans show some expected separation of defensive responsibilities from the midfield roles - though the idea that Evans' switch may herald increased passing responsibility for the backline remains an interesting question. Nevertheless, Marco Pappa's absence is apparent on the chart and was noticeable on the field. A wide midfield pairing of Lamar Neagle and Andy Rose cannot take on the same distribution responsibility.
The 2015 squad may also never quite look like the 2014 Sounders. Through the first 4 games, Tyrone Mears (marked as M on the the plots) has persistently adopted a lesser share of team defense than DeAndre Yedlin's average performance from 2014. 2015's fullbacks may be better or worse than the 2014 version, but the trend thus far is that they will be clearly different.
Edit: Slight modifications to third figure.