PScore: Modeling Tactics in MLS by game state - August 2016 / by Jared Young

By Jared Young (@jaredeyoung)

Friday August was 12th was Elephant Day and it’s seems like as good a time as any to free some elephants from our rooms and get them back into the wild where they belong. What elephants? What rooms, you might ask? Glad you asked. The room we are in right now is one where soccer tactics are turned into numbers. For those new to the Pscore series the idea is to very simply describe soccer tactics with two numbers, one offensive and one defensive. What tactics are quantified? From an offensive point of view we want to know if a team desires possession of the ball or is more direct with their play. From a defensive point of view we want to know how high up the pitch a team pressures their opponent. All styles can be effective but two in particular are generally used in combination. On the proactive side you have your Barcelona’s of the world that look to work possession on offense and counterpress when they lose the ball to get it back quickly. On the reactive side there are examples like Leicester City that will sit their defense deeper and then play directly on the counterattack once in possession. As you’ll quickly see Major League Soccer sports a handful of those type of clubs and a few different styles. If you are curious how these numbers are developed I’ve written about that in detail before and you can read it here.

What’s the elephant in the room? Well up until now the numbers have not been adjusted by game state, meaning the score does not come into play. As we all know, the score does change a team’s tactics. When a team is losing they must push forward and try to get the ball and keep possession. When a team is winning they are prone to sit deeper as defense become a priority. Well, I’m happy to say that adding game state data to this analysis bears that out quite clearly.

Before we get there let’s look at the teams on average this season.  The offensive score from 0 to 1 is on the horizontal axis. The score ranges from most direct passing at 0 to most indirect passing at 1. The defensive score is vertical which is the passes allowed per defensive action in the attacking half of the field.

Observations:

  • Not a ton has changed since the first review earlier this season. Sporting Kansas City appears to be the league’s most proactive team this year with the New York Red Bulls more aggressive defensively, but more direct offensively.
  • Houston and Chicago, the two teams at the bottom of their respective conferences, are the most reactive teams in the league.
  • DC United has gotten much more aggressive defensively but they are the league’s most direct passing team

Now to the fun stuff and where I put you to work. Below is a chart that shows all MLS teams tactically during even, losing and winning game states. You can toggle between the three options in the upper left hand corner of the chart by using the forward and backward arrows. Notice how all the of the teams shift to the upper left when in the winning position. This indicates that teams sit their defenses deeper and pass more directly, exactly what we’d expect. When in the losing game state the teams jump down to the lower left. They become more possession oriented in their passing and press higher up the pitch. You can examine individual teams by selecting or deselecting them on the right. Two teams I recommend comparing are the Portland Timbers and the Philadelphia Union. Both have very different approaches based on game state but are not that far apart tactically on average. 

In case you don’t want to toggle you can select teams on the below chart and see how they change at the same time. Green indicates winning, blue indicates even and red indicates losing. Here you can see more clearly the shift from winning in the upper left (reactive) to losing in the lower right (proactive).

And lastly here is a plot of the variances by game state. The higher the variance the more a team changes tactics based on game state.

Some observations:

  • There are some teams like the Portland Timbers that change their tactics dramatically based on the score of the game and teams like the Philadelphia Union who barely change at all. To know this would have to be an advantage for coaches as they prepare their team. If Portland goes down a goal you know they will get much more aggressive while the Union will stick to their style of play.
  • FC Dallas and Columbus both play similarly to Union in that they don't change their style of play based on the score. The success of the Union and Dallas this year suggest that a team can do well sticking to their style of play. 
  • The even game state is fairly close to the team average as expected which shows that the tactical analysis we've been looking at is a good overall view of how a team plays when equally concerned about defense and offense and playing in their ideal balance on both sides of the ball.
  • The Seattle Sounders are alone in their style this year. They sit deep defensively but are also utilize short passing to maintain possession. The issue with that style is that the lack of defensive pressure provide space behind the opponent's offense and is best exposed by direct passing. This could be one of the reasons why they are struggling offensively. What's more bizarre is that they have applied more defensive pressure when in the lead. 

We can safely usher the elephant out of this room now and move to the next phase of modeling tactics.