The defensive luck signal measures the gap between goals actually conceded and expected goals against (xGA), the model's estimate of how many goals a team should have conceded based on the quality of chances they allowed. When a team concedes significantly more than their xGA, it suggests finishing luck running against them, goalkeeping underperformance, or some combination of both. When a team concedes far fewer, the opposite is true.
It matters because xGA variance is one of the most regression-prone signals in football. Teams rarely sustain large gaps in either direction across a full season, which means the clubs at the extremes of this list are living on borrowed time, for better or worse.
Most Cursed by Defensive Luck
1. Athletic Club (48 conceded vs 37.7 xGA, +10.3) No team in La Liga has been punished more harshly by the finishing gods. Athletic's defense has allowed chances worth roughly 38 goals. They have conceded 48. That is a gulf wide enough to flip several results across a season.
2. Valencia (48 conceded vs 40.5 xGA, +7.5) Valencia have matched Athletic's raw concession total on a considerably worse underlying defensive profile, which means their xGA gap is slightly less dramatic. Still, 7.5 goals above expectation is a painful surplus.
3. Alaves (49 conceded vs 43.2 xGA, +5.8) Alaves have genuine defensive problems. Their xGA of 43.2 is not flattering. But conceding 49 adds a layer of misfortune on top of structural issues.
4. Real Sociedad (52 conceded vs 47.6 xGA, +4.4) The raw total of 52 goals conceded is the highest on this list. The xGA suggests they should be shipping plenty regardless. The 4.4-goal surplus is just salt in the wound.
5. Real Betis (41 conceded vs 38.2 xGA, +2.8) A modest gap, but enough to land Betis in the top five. Their defensive structure is reasonably sound. The scoreline just hasn't reflected it.
Most Blessed by Defensive Luck
1. Barcelona (30 conceded vs 40.6 xGA, -10.6) Barcelona's defense has been allowing chances worth over 40 goals. They have conceded 30. That 10.6-goal underperformance is the single largest blessing in the division, and it raises a fair question about how much of their defensive record is sustainable.
Sometimes the best defense is someone else missing.
2. Elche (50 conceded vs 57.3 xGA, -7.3) Elche are conceding at a rate that would alarm anyone. The thing is, it should be worse. Their xGA of 57.3 suggests a defense in genuine crisis, partially masked by 7.3 goals' worth of opponent profligacy.
3. Real Madrid (31 conceded vs 36.4 xGA, -5.4) Madrid's defensive numbers look elite on paper. The underlying data says they are merely good. A 5.4-goal gap is meaningful but less extreme than Barcelona's, which is worth noting in the broader title race context.
4. Mallorca (51 conceded vs 55.5 xGA, -4.5) Like Elche, Mallorca have been bad defensively by any measure. Their blessing is relative. Conceding 51 instead of the expected 55.5 has likely been the difference in a relegation fight.
5. Getafe (34 conceded vs 38.4 xGA, -4.4) Getafe's defensive reputation continues to outpace the quality of chances they actually allow. A 4.4-goal underperformance suggests some of that stinginess is borrowed.
What This Tells Us
The range from Athletic Club's +10.3 to Barcelona's -10.6 spans over 20 goals of variance on a single defensive axis. Historically, gaps of this magnitude regress substantially. Teams running hot on the blessed side tend to concede more in the closing stretch. Teams on the cursed side tend to tighten up, or at least stop seeing every half-chance ripple the net.
The implication for the title race is uncomfortable for Barcelona and encouraging for Athletic Club. Regression does not ask permission.
