Possession
Who gets the open chances? It has been shown that the right formula uses exponent 3.
Chance distribution: possession % is misleading!
With 60% possession you win almost 8 open chances out of 10.
The possession percentage you see when you set your lineup is just the ratio between the two midfields, not the share of chances you will get. At 60% your midfield is worth 1.5 times the opponent's (15 against 10), and you take about 77% of the open chances.
Open chances are shared out according to the cube of the midfield:
where a is your midfield and b is the opponent's.
| Possession | Midfield (you vs opponent) | Open chances |
|---|---|---|
| 50% | 10 vs 10 | 50% |
| 55% | 12.2 vs 10 | 65% |
| 60% | 15 vs 10 | 77% |
| 65% | 18.6 vs 10 | 86% |
| 70% | 23.3 vs 10 | 93% |
| 75% | 30 vs 10 | 96% |
The curve is S-shaped. Each possession point is worth about 3 points of chances between 50 and 55%, about 2.5 between 55 and 60%, about 2 between 60 and 65% and about 1 between 65 and 70%. Above 70% the returns become marginal.
The formula only applies to open chances. It does not cover the chances assigned to each team or special events.
Check: across almost 280,000 real matches, Exp3 matches the data in every possession band, far better than the "Tasos" formula (a²/2b², derived from a devblog chart).
| Possession | Matches | Actual | "Tasos" | Exp3 |
|---|---|---|---|---|
| 51–54% | 104,291 | 58.8% | 60% | 58.7% |
| 55–59% | 89,705 | 70.4% | 72% | 70.4% |
| 60–64% | 48,534 | 81.5% | 81% | 81.4% |
| 65–69% | 22,154 | 89.6% | 88% | 89.4% |
| 70–74% | 9,369 | 94.5% | 92% | 94.4% |
| 75–79% | 4,173 | 97.4% | 95% | 97.4% |
Actual vs formulas, for every possession point
Share of open chances won by the team with more possession. The Exp3 line almost completely overlaps the actual one.