Barcelona travelled to San Sebastian with Hansi Flick's 4-3-3 in full flow, generated 3.7 expected goals from 25 shots, had a goal and a penalty taken away by VAR, and lost 2-1. The Luck Index registered the impact.
A Match of Three VAR Decisions
The tone was set early. Fermin Lopez found the net on 8 minutes, only for VAR to chalk it off. Barcelona kept pressing. They created chance after chance, racking up shots from all angles. By the time Oyarzabal gave Real Sociedad a 1-0 lead against the run of play on 32 minutes, assisted by Guedes, Barca had already produced more xG than most sides manage in an entire match.
Then came the moment that encapsulated the afternoon. Just before half-time, Lamine Yamal won a penalty. VAR reviewed it. Penalty cancelled. Barcelona went into the break trailing despite doing everything right.
Sixty Seconds of Hope
Flick threw on Lewandowski, Rashford, and Cancelo at the hour mark. The gamble appeared to pay off when Rashford equalized on 70 minutes, Yamal providing the assist. The Reale Arena fell quiet.
For exactly 60 seconds.
Guedes restored Real Sociedad's lead on 71 minutes, his second involvement in a goal. Barcelona had held parity for one minute. Their 3.7 xG, their 25 shots, their 18-shot advantage - none of it mattered.
The final 20 minutes descended into frustration. Eric Garcia, Lewandowski, and Fermin Lopez all picked up yellow cards. Carlos Soler's red card on 87 minutes, upgraded by VAR, came too late to change anything. Frenkie de Jong added a yellow in the 100th minute for good measure.
What the Data Says
Barcelona's 3.7 xG from 25 shots against Real Sociedad's 1.0 xG from 7 shots represents one of the largest xG gaps in La Liga this season. Sociedad converted at a rate nearly three times their expected output. Barcelona converted at roughly one-quarter of theirs.
The Luck Index doesn't deal in narratives about heart, desire, or tactical plans. It deals in probabilities. And the probability of losing a match where you generate 3.7 xG and concede 1.0 is extremely low. Barcelona found that probability anyway.