I’m always on the lookout for new ways to visualize data in the hopes that it might lead to a better understanding of the data. In the first leg of the tie between Real Salt Lake and Seattle Sounders FC, the Sounders midfield was completely MIA for large portions of the game while RSL enjoyed large periods of maintaining possession. I wanted to come up with a generic way to visualize similar situations. I decided to use a stacked time series, broken down by position. In the examples below I looked at completed passes by position. Any metric could be used and you could also use different variables to slice the data. Another thing to look at could be which third of the pitch the event occurs in. I like the idea of the stacked time series because it allows you to look at the team total as well as some finer detail at the same time.
When I looked at the first leg of Seattle Sounders FC – Real Salt Lake, one thing that was immediately apparent was the inability of Seattle’s midfield to have an impact on the match. In the above diagram, the same thing can be seen as depicted by moments when the orange band becomes very narrow. The wider the band, the more passes completed and Seattle’s midfield wasn’t getting it done. One thing that wasn’t obvious at first was how much Seattle’s forwards were involved either side of half time. Seattle enjoyed a bit more possession during this time. Most of the passes by Seattle’s forwards during this time were near midfield. Did Seattle enjoy more possession because their forwards tracked back and provided extra numbers in the middle?
Filtering the data set down to just passes in the final third, Seattle’s early problems are again apparent. What was interesting was that even though Real Salt Lake was dominating the first 30 minutes, their fullbacks didn’t seem to venture too far forward. The above graph is just for completed passes, but looking at all passes, there was only 1 pass attempted by a defender in the final third in the first 28 minutes. Later in the game, RSL’s fullbacks were able to get more forward and during this time, RSL scored two goals.
Seattle had a 3 goal deficit to overcome in the second leg and needed to press early on. Again there were moments where Seattle’s midfield were not very involved, but this is somewhat expected given that by the 21st minute they had already replaced 2 midfielders due to injuries. What’s interesting in this graph is Seattle’s heavy reliance on their defenders to move the ball, particularly towards the end of the match when they were looking for the equalizer.
The above graph is completed passes in the final third. Seattle got their fullbacks forward early and often while Real Salt Lake parked the bus. RSL really had no intention of trying to score and rarely ventured very far forward. Also of note is the absence of passes in the final third by forwards towards the end of the game as RSL successfully defended the long ball approach.
This visualization technique allows us to look at several dimensions of data over time. When data is presented in summary form, a lot of the context about the momentum of the match is lost. By looking at the stacked timeseries, the ebbs and flows of each team become apparent. If you were to overlay key events the data could be even more revealing.
The diagrams above were produced using Processing and data from Opta’s MLS Chalkboards.