Goals decide matches, but they are rare and noisy: a deflection, a goalkeeping error or a missed sitter can swing a game. Expected goals (xG), expected assists (xA) and passes per defensive action (PPDA) measure what happened underneath the scoreline — how good the chances were, how dangerous the passes were and how hard a team pressed. Used well, they show which teams and players are performing better or worse than their results.
Expected goals (xG)
Every shot gets a value between 0 and 1: the probability that a shot like it ends up in the net, based on a very large set of past shots. Zero is a chance that cannot be scored; one is a chance a player would be expected to score every single time. A team's xG for a match is the sum of the values of all its shots.
Models differ in the details, but the main inputs are similar: distance and angle to goal, the body part used, the type of assist (cross, through ball, cut-back), whether the shot came from a set piece or open play and, in more advanced models, where the defenders and the goalkeeper were. Penalties are the exception: because every penalty is taken from the same spot, most models give them a fixed value of about 0.76–0.79, depending on the provider.
How to read xG
- Goals vs xG. A team that scores far more than its xG over a long run is finishing unusually well — or getting lucky. Over time, most teams drift back towards their xG.
- xG against. The quality of chances a team concedes. It is often a better guide to defensive strength than goals conceded.
- xG difference (xGD). xG for minus xG against: one of the most reliable single numbers for how good a team really is.
- Non-penalty xG (npxG). Removes penalties, which depend on decisions more than on chance creation.
Expected assists (xA)
xA does for passes what xG does for shots. In Opta's version, it estimates the likelihood that a completed pass becomes an assist, using the type of pass, where it was made and received, the pattern of play and its distance. Crucially, the passer gets credit whether or not the receiver actually shoots, so a perfect cut-back that the striker miskicks still counts.
That makes xA a measure of chance creation that is not distorted by teammates' finishing. A midfielder with many assists but low xA may be benefiting from great finishing; one with high xA and few assists may simply be unlucky.
Check the definition: some websites use a different stat — the xG of the shots that a player's passes led to. That version only counts passes followed by a shot. Before comparing "xA" from two sites, check which one each is using.
PPDA: measuring the press
PPDA stands for passes per defensive action. It is measured in the 60% of the pitch nearest the opponent's goal — the whole of the opponent's half plus a fifth of your own. The opponent's passes in that zone are divided by the defensive actions (tackles, interceptions, challenges and fouls) made there by the team without the ball.
A low PPDA means the team allows few passes before it engages: it presses high and often. A high PPDA means it sits off and lets the opponent keep the ball. Neither is "good" on its own; it describes a style.
| Team, 2021/22 | League | PPDA | What it shows |
|---|---|---|---|
| Barcelona | La Liga | 7.26 | Lowest in Europe's top five leagues |
| Liverpool | Premier League | 8.62 | Lowest in the Premier League |
| Newcastle United | Premier League | 14.57 | Among the six highest in the top five leagues |
| Everton | Premier League | 14.63 | Among the six highest in the top five leagues |
| Wolverhampton Wanderers | Premier League | 14.78 | Among the six highest in the top five leagues |
| Norwich City | Premier League | 16.93 | Joint highest in the top five leagues, with Troyes |
Data: Premier League, "Passes per defensive action: explained" (published 19 February 2025), figures for the 2021/22 season.
How to use these stats without being fooled
- Use a big enough sample. One match of xG says little; ten or more start to show a pattern. For individual players, a full season is better.
- Look at the game state. A team that leads early often drops deeper, so its xG against rises and its PPDA goes up. That is tactics, not decline.
- Compare like with like. Different providers' models give different numbers. Do not mix sources in one comparison.
- Read the stats together. A side with a low PPDA, high xG and low xG against is dominating games. A side with a big gap between its goals and its xG may be due a correction.
Key point: xG, xA and PPDA do not replace watching matches. They tell you where to look: which results were deserved, which players create more than their assists show, and which teams really press.
Sources
- Evolving expected goals (xG) — Opta Analyst
- What are expected assists (xA)? — Opta Analyst
- Passes per defensive action: explained — Premier League
Premier League and Champions League by the numbers.