Time → Chemistry

Practice makes perfect. Teams that share more on-pitch time develop chemistry faster — through rehearsal of patterns, shared mental models, and trust built in repetition. With WC22 tracking data we can finally test that hypothesis, not just assert it.

The soft case first

Before we cut to the numbers, the qualitative case for time-builds-chemistry is everywhere in football. Four examples worth holding in your head:

Club teammates carry pre-built chemistry into national squads.

Germany's 2014 World Cup spine was Bayern Munich (Neuer, Boateng, Lahm, Schweinsteiger, Müller). Spain's 2010–2012 dynasty was Xavi–Iniesta–Busquets plus the Barça–Madrid axis. National-team chemistry doesn't have to be built from scratch when half the squad already plays together every week.

Long-tenured tactical systems amplify chemistry.

Klopp's Liverpool gegenpress, Guardiola's positional play at City — the famous “5-second rule” counter-press only works because the eleven players have rehearsed it hundreds of hours. The system is a chemistry multiplier, not a substitute.

New squads underperform their talent.

The 2003 Real Madrid galácticos, last-minute international call-ups, freshly assembled super-teams — they almost always look less than the sum of their parts for the first few months. The roster is elite. The pattern bank is empty.

The literature backs the intuition.

Geir Jordet's scanning research (visual exploration frequency predicts pass success) shows chemistry is measurable, not mystical. Academic work presented at conferences like MIT Sloan extends that line. Frame-level tracking is the next layer of evidence on top of the same idea — full citations on Methodology.

History Index — our shared-time proxy

We need a measure of “how much have these specific players shared a pitch before the tournament started?” The History Index is the simplest possible version: the count of WC22 squad players who have at least one current or former club-mate inside their own national squad. The denominator is squad size N (typically 23–26). It's coarse, but it's interpretable and it doesn't depend on league-by-league minutes coverage.

The four densest histories in Qatar. France: 20 of 24. Spain: 19 of 20. Argentina: 18 of 24. Portugal: 19 of 24. These are squads with overlapping club careers — groups that arrived at the tournament already understanding each other.

History Index vs Team Chemistry Density (ρ = +0.348, p ≈ 0.055, n = 31)

Each dot = one WC22 squad. X = History Index (squad players with a national-squad club-mate). Y = TCD, the count of same-team pairs with attention-weighted JOI per 90 ≥ 0.4. Gold ring marks the four semifinalists.

What correlates with chemistry?

Spearman rank correlations against the 31 WC22 sides. Time-based proxies all point the same direction; FIFA Overall is also positive but operates through a different channel (talent concentration, not rehearsal).

Hypothesis	Spearman ρ	p	n	Reading
History Index → Team Chemistry Density	+0.348	≈ 0.055	31	Directional. The headline time→chemistry leg.
History Index → Mean AW-JOI90	+0.38	0.034	31	Same direction at per-pair intensity, slightly stronger.
FIFA 23 Overall → Team Chemistry Density	+0.51	0.004	30	Top-rated nations also have dense chemistry — players concentrate at elite clubs.
Pair shared club-seasons → pair AW-JOI90	+0.05	0.003	3,443	Pair-scale: tiny effect. Counted in seasons a pair were actual club teammates (no estimated minutes). Time matters at squad scale, not pair scale.

What the data says

Time is directionally predictive, not a deterministic input. Squads with high History Index tend to land higher TCD, but the relationship is loose: p ≈ 0.055 on n = 31 is borderline — we describe this as directional and suggestive, not “significant.” That's the honest read. There are also visible exceptions on the scatter: Morocco's TCD is much higher than its History Index would predict, and a few high-history squads (Germany among them) didn't translate shared club history into a dense network in Qatar. Time helps. Time isn't destiny.

One more thing worth landing. What the History Index predicts — TCD — captures pair value that the moment-by-moment frame data picks up on the ball and off it. Time builds both. That's why the same time→chemistry story shows up whether we measure chemistry from attention on the ball (where the obvious pass goes) or attention off the ball (where the runs that create the pass come from).

For context: the next leg of the story — chemistry → winning — runs at ρ = +0.704 (TCD → WC22 finish), compared to ρ = +0.548 for FIFA 23 Overall → finish. Time→chemistry is the weaker leg of the arc; chemistry→winning is the stronger one.

Next up. We've shown how chemistry develops — shared time builds it, with caveats. The question that follows is the one that pays: does chemistry actually win? Four semifinalist case studies are waiting on the next tab. Chemistry → Winning →

Method & sources

History Index is computed pre-WC22 from PFF rosters and the player_club_history_wc22 table: for each WC22 squad player, we check whether any other player on the same national squad has shared a club (current or former) with them. The count of yes-answers is the squad's History Index; the denominator is squad size N.

Team Chemistry Density (TCD) is the count of same-team WC22 pair-seasons with attention-weighted JOI per 90 ≥ 0.4 — the same metric and threshold used on the Chemistry Leaderboard. AW-JOI itself is the per-frame product of the two players' ball-attention multiplied by max(ΔP_score, 0), accumulated across the tournament. See methodology §attention for the full pipeline.

Tournament result rank: winner=1, RU=2, 3rd=3, 4th=4, QF losers 5–8 by group-stage points, R16 losers 9–16, group-stage exits 17–32 by points then goal differential.