Chelsea beat Blackburn Rovers pretty handily today and I wanted to roll out a new Tableau toy in analysing the game. Having seen this pass completion graph from the excellent Blackpool tactics blog Tangerine Dreaming, I was inspired to come up with a tool that showed a rolling average of pass completion percentage without neglecting pass frequency. Chart and explanation after the jump:
Figure 1: Pass Completion and Frequency, Chelsea vs. Blackburn, 1/15/10. Powered by Tableau
I think that's pretty cool. The y-axis represents a rolling average of pass completion for the marked five* minute period and each five minutes before and afterwards, while the thickness of the line denotes how many of the passes in that time belonged to each team, something which I'm going to call play percentage for very little good reason. A mouseover will show passes attempted in the five minutes highlighted. Chelsea out-passed Blackburn by a ratio of more than two to one (as well as out-shooting them by a 31-4), so it's no surprise to see that they comfortably bested them in completion percentage as well as total passes attempted.
I'm not sure if this is particularly valuable in terms of analysis - as you can see the most obvious periods of Chelsea dominance here were simply the result of Blackburn sticking ten men behind the ball and leaving the home side passing the ball along the halfway line - but it sure is a neat way to dump a lot of data in all at once. Oh, and this is an interesting little factoid: Chelsea's best five-minute passing spell? The five minutes after Josh McEachran came on. Surprise!
We'll have a more fully fleshed out analysis post, complete with full formation chart for you tomorrow.
*Five minutes plus any injury time, of course.