The probability that a shot becomes a goal, based on historical data. A penalty = 0.76 xG. A header from 12 yards = 0.08 xG. If a team has 2.5 xG but scored 1 goal, they were unlucky. If they have 0.8 xG and scored 3, that's unsustainable — regression is coming.
Measures pressing intensity. Lower = more aggressive pressing. Arsenal 2024-25: PPDA of 8.2 (very aggressive). Burnley under Dyche: PPDA of 14+ (sit back). Anything under 10 means a team presses hard. Over 12 means they wait for you to come to them.
A pass or carry that moves the ball at least 10 yards toward the opponent's goal. This measures who's actually driving play forward vs. passing sideways. De Bruyne leads the PL in progressive passes every year. It's why he's considered the best midfielder — he always goes forward.
The probability of a pass becoming an assist, based on the shot opportunity it creates. A through ball to a 1-on-1 = high xA. A cross into a crowded box = low xA. Players with high xA but low actual assists are creating chances that teammates are wasting.