How Is Zone Time Calculated?
WhoScored.com publishes territory info for each PL fixture which tells us which areas of the field play has taken place in. Usually, that territory info looks something like this:
So, this tells us what percentage of play took place in the attacking, neutral, and defensive thirds of the pitch. I take this info, turn it into a per90 number and assign the two teams their minutes spent in each zone of the pitch.
Then I run the same calculations for all 380 PL games. And the final table looks like this:
|Team||O Zone Time||N Zone Time||D Zone Time|
This table is sortable so have a play around.
With this information we can create a couple of visualizations that help us to get a better understanding about the information.
Offensive Time & Defensive Time Per Game
The further right a team is on this chart the more time per game they spent in the attacking zone. The lower a team is on this chart the less time spent in their defensive end per game
Man City spent the fewest minutes per game in their own defensive end and were just pipped by Chelsea for the highest minutes per game spent in the attacking zone.
West Brom look to be a team in an odd spot on this chart, but the amount of time spent losing during games likely meant that the Baggies were chasing games and pinning their opponents back for large sections of games.
Liverpool are another odd team: some score effects (lots of time leading) and Rodgers' systems likely led to Liverpool spending more minutes per game defensing than they did attacking. With Liverpool's defense likely a weak spot, it may well have been a designed tactic to sit deep and prevent the Skrtel's and Johnson's of this world being exposed in 3 on 3 or 4 on 4 situations. This tactic wasn't entirely successful.
Offensive/Defensive Zone Time Differential
If we take team's attacking time and defensive time and run a simple subtraction we can discover which teams spend more minutes per game attacking than defending, and by how many minutes per game.
It is clearly a good thing to spend more minutes per game attacking than it is defending, but for some teams there are tons of score effects (more time leading can lead to sitting back and defending in your own defensive zone) at play which can skew some of the numbers seen above. But the very best teams, Man City and Chelsea, will still dominate territory and attacking zone time despite leading frequently in games. Conversely, the worst teams in the league will still get stuck in their own defensive zone despite trailing frequently in games.
Looking at the repeatability from 1st 19 games to the 2nd 19 games we get this:
Offensive Zone Time r2=0.64
Defensive Zone Time r2=0.60
Attacking ability is likely more repeatable across a number of different stats than defensive ability. There's also some issues with looking at 19 game splits, things like schedule, injury, manager changes, January signings and sales. A whole host of things basically.