[DM] xG가 설명하지 못하는 팀, 아스톤 빌라

Hours after Morgan Rogers’ fantastic goal cemented Aston Villa’s spot in the title race, we saw the unusual sight of a Premier League club taking aim at the statisticians.

Amid Villa's incredible run of 10 wins in their last 11 PL games, the numbers guys have argued that their success isn't sustainable. They cite the number of goals Villa has scored from outside the box (10 goals from 42 shots, 23.8%) and their relatively low Expected Goals (xG) figures as evidence.

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The well-known @xGPhilosophy account posted on X (Twitter) that Rogers' winning goal against West Ham last Sunday had an xG value of just 0.02 (a chance that would be missed 98 times out of 100).

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At 10 PM Sunday night, seemingly having had enough, Villa's official account posted a clip of Rogers' winning goal with the caption '0.02 xG 😉'. This shade racked up 1.2 million views.

We spoke to the people running the @xGPhilosophy account, who requested anonymity. It's fair to say that a significant part of the Villa social media community took their analysis as a personal attack. In particular, a post suggesting that Villa rightfully belongs around 15th place, just a few points ahead of currently struggling bottom-of-the-table Wolves, angered Villa fans.

@xGPhilosophy Team Member: "After we put up that post, a Villa fan replied, 'Aston Villa is third based on points earned and performance,' which was fair and got 2.5 million views. We just dropped a casual joke like, 'We'll see about that,' and then things blew up from there. Currently, there's no clear reason why Aston Villa is overperforming their xG. This usually happens when a striker is hitting peak finishing form. This happened previously at Tottenham with Harry Kane and Son Heung-min. They were elite finishers who consistently outperformed their xG. But this season, Ollie Watkins is actually doing the opposite, scoring fewer goals than his xG suggests. Instead, guys like Rogers, Cash, and Buendia are scoring from long-range shots. If you look at Villa's recent results and xG, they've won seven consecutive matches across all competitions by just one goal. This is extremely rare in a variable sport like football, and since tough fixtures are coming up, we predict Villa will revert back to the normal pattern."

The gripes about xG aren't just limited to Villa fans online. It has also made the club uncomfortable, and the stats reveal something interesting. According to Opta, since Emery took over Villa in November 2022, they've scored 199 goals—25 more than their xG. They've conceded 155 goals, which is 13 fewer than their Expected Goals Against (xGA) suggests.

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Looking at the Expected Points table (statistics using xG), Villa has earned 44 more points than expected under Emery in the PL (172 expected points vs. 216 actual points). Emery has managed 117 PL games at Villa, finishing 7th (mid-season arrival), 4th, and 6th. This is precisely where the explanatory power of existing statistical models is called into question. Any team can have a period of luck lasting weeks or months, like Villa has shown recently. But having this luck persist for over three years seems highly improbable. Villa maximizing the chances they create is nothing new. Since Emery's arrival, no team has accumulated more actual points relative to their expected points than Villa.

The xG model assesses the quality of chances. Taking Rogers' winner against West Ham as an example, the xG model assigns a value of 0.02 because it determines an 'average' top-flight player would score from that position once every 50 attempts. However, there are crucial underlying conditions. We understand that Rogers has been doing extra shooting training at the training ground for a while and has mastered the knuckleball shot. The 'average' Premier League player cannot replicate this knuckleball repeatedly, nor do most players put in the dedicated effort Rogers does. Therefore, Rogers performing better than others from this position isn't just down to luck.

Villa believes that the excessive obsession with their xG disregards the efforts of Emery and the players. Just as Rogers isn't an 'average' player, Emery isn't an 'ordinary' manager. Emery does receive and refer to xG stats, but they aren't the decisive factor in his analysis. Emery prepares customized tactics for every match, adjusting Villa's formation to counter the opposing team. The level of detail in this preparation is beyond imagination, and when Emery says Villa 'feels comfortable within our structure,' he means ensuring every player understands exactly what is required, down to the smallest detail.

Emery moves players around until they are in the exact position he wants, and afternoon video sessions can last over an hour. Individual meetings conducted in front of a laptop tell each player precisely what they need to do—for example, the specific penetrating runs to make when a teammate has the ball, or the angle they must position themselves at when facing a particular opponent.

If the England Cricket team's 'Bazball' strategy follows a single approach regardless of the opponent, match situation, or conditions, Emery is the complete opposite. Betting expert Alan Alger also believes that Emery has found a way to counteract the xG patterns.

Alger: "All the xG experts think Villa will collapse, but I don't think so. Emery has found a way to mitigate this through the defensive style he demands from the team. Emery doesn't seem to mind Villa conceding several low-quality chances per game. This means opponents can accumulate a relatively high xG value even without creating many good opportunities. Two years ago, when West Ham beat Arsenal 2-0 away, some Arsenal fans claimed they were unlucky because their xG was 2.79. But if you look closely, all of Arsenal's chances had an xG of around 0.05. In other words, they only created a high volume of low-quality chances."

Alger argues that xG is no longer the be-all and end-all metric. When xG first emerged in the gambling industry 20 years ago, it was revolutionary. But now, there are other metrics that bettors refer to. We understand that most PL clubs pay attention to xG, but it's rarely the top priority in meetings, and players usually only know about it when staff tell them, rarely seeking it out themselves.

Alger: "Professional bettors made serious bank off xG for years. But now the models are so sophisticated that xG is maybe only the fifth thing they consider. They look at the number of penalty box entries, the movement of overlapping players finding space to create assists. They also focus on specific player combinations. For instance, they might figure out that a specific combination of three attackers creates an average xG of 2.5 per game. Things are much more granular now."

There's no way Emery doesn't know this stuff. If Emery were your coworker, he'd be the one who arrives first, leaves last, and starts the next report immediately upon getting home. Everyone at Bodymoor Heath (Villa's training ground) calls him 'Boss.' He is kind and polite but not one for small talk.

Emery has said he didn't come to Villa to waste time. He is one of the highest-paid managers in the PL, alongside Pep Guardiola and Mikel Arteta, but Villa co-owner Nassef Sawiris is definitely seeing returns on his investment.

Last season, Emery once said, half-jokingly, that players should be so focused they think about football even in their dreams. Emery himself rarely thinks about anything but football. Arriving early at Bodymoor Heath and leaving only after dark, Emery has a terrifying belief in his own abilities, which he has spread to the players. Regardless of what the numbers say, this fact alone is enough to make you believe Villa can stick it out till the end.

- The difference between the ranking based on xG values this season and the actual ranking.