PPDA and the Problem of Measuring the Press
Passes allowed per defensive action became a popular shorthand for pressing intensity. It is a useful number, but only if you know what it leaves out.
Pressing is one of the defining features of modern football, yet it is surprisingly hard to measure. A team can press aggressively without winning the ball, or win the ball high up the pitch without pressing in any organised way. Analysts have developed a range of metrics to capture pressing, and among the most widely cited is PPDA: passes allowed per defensive action.
How PPDA is calculated
PPDA compares how many passes an opponent makes in a given area of the pitch with how many defensive actions the pressing team makes there. Definitions vary between data providers, but the general approach is:
- Count the opponent's passes in a defined build-up zone, typically the part of the pitch furthest from the pressing team's goal.
- Count the pressing team's defensive actions in that same zone, such as tackles, interceptions, challenges and fouls.
- Divide the first figure by the second.
The result is the average number of passes the opponent is allowed before the pressing team makes a defensive action. A low PPDA suggests intense pressing: the opponent is not permitted many passes before being challenged. A high PPDA suggests a more passive approach, with opponents given time to build.
Why it became popular
PPDA has several attractions. It uses event data that is widely available, it is simple to calculate and explain, and it produces a single number that can be compared across teams and seasons. It captures the basic intuition that an aggressive pressing side disrupts its opponent's passing sequences early.
For teams known for high-intensity approaches, including those built around counter-pressing, a low PPDA often matches how the team is perceived.
PPDA is a measure of how quickly a team interrupts its opponent's passing. It is a proxy for pressing, not a portrait of it.
What PPDA misses
The metric's simplicity is also its weakness:
- Pressure without actions: much effective pressing works by forcing a long ball or a poor pass rather than by tackling. If the opponent simply clears the ball, no defensive action may be recorded, yet the press has done its job.
- Opponent style: teams that play long from the back make few passes in their own half, which changes the ratio regardless of how the pressing team behaves.
- Game state: a team that is leading may drop off, while one chasing a result may press harder, so match-level PPDA reflects circumstances as well as intent.
- Organisation: PPDA says nothing about whether the press is coordinated, whether it covers passing lanes or whether it leaves the team exposed.
- Fouls: counting fouls as defensive actions means a team that stops play frequently can appear to press intensely.
Other ways to measure the press
Analysts have developed complementary measures to fill these gaps. With event data, one approach is to count high turnovers, meaning possessions won within a certain distance of the opponent's goal, and to track how often those turnovers lead to shots. Where data records each occasion a player applies pressure to the ball carrier, pressures can be counted directly and mapped across the pitch.
Tracking data, which records the positions of all players throughout a match, allows richer analysis still: measuring team compactness, the distances between lines and how quickly players close down space. These approaches come closer to the collective, positional nature of pressing that coaches such as Arrigo Sacchi emphasised long before such numbers existed.
Using PPDA sensibly
PPDA remains useful as a first indicator, particularly for comparing teams across a season. It works best alongside other information:
- Where on the pitch a team wins the ball.
- What happens in the moments after the ball is won.
- How opponents respond, for example by going long.
- Context such as game state and the quality of the opposition.
A single season-long figure can also hide variation. A team may press ferociously against some opponents and sit deeper against others, and the average will describe neither approach accurately. Splitting the number by opponent or by game state often reveals more than the headline figure.
As with expected goals, the most useful approach is to treat the number as a question rather than an answer. A low PPDA says that something is happening. Understanding what, and how well, requires looking further.