The opponent's defensive organization fundamentally changes the problem a team must solve in each possession phase. Three primary block types: (1) High press — opponent presses immediately after ball receipt, anywhere on the pitch; creates time and space pressure in build-up, requires fast decision-making and ability to play through pressure; (2) Mid block — opponent defends between the two penalty areas, allowing build-up but pressuring progression; (3) Full retreat (deep block) — opponent defends near their own goal, making penetration the primary challenge. Any possession analysis that ignores which block type was active is mixing three different problems.
Classify each possession by opponent block type at the moment of possession start. Proxy measures: average defensive line height (high = pressing, low = deep block), time to first opponent pressure event after ball receipt, and proportion of opponent touches in each pitch third. Tag each possession-phase moment with the active block type. This enables filtered analysis: "our build-up success rate against high press is X% vs. Y% against a mid block" — which are genuinely different metrics requiring different tactical responses.
Context filtering by opponent block type reveals that a single team's statistical profile bifurcates dramatically. A team averaging 60% possession may have 72% against low blocks and 48% against high presses — and the tactical problems in each context are fundamentally different. Analyzing aggregate possession quality without conditioning on block type produces conclusions that apply to neither situation specifically.