Barcelona's midfielder Xavi Hernandez re

Compromised numbers: Why the statistic you see may not be actual possession


One of the amazing statistics to come out of last Wednesday’s UEFA Champions League match was the possession number. Barcelona was reported by UEFA was having held the ball 72 percent of the time, an amazing figure against a club of Chelsea’s caliber. For those who have tried to find significance to correlations between possession and victories, the number must have been both remarkable and beguiling. After all, Barcelona lost, giving more credence to the hypothesis’ main qualm: What if one team doesn’t care about holding the ball?

The next day, the possession story got even more confusing. Supreme stat overlords Opta reported that Chelsea had only managed 20 percent of the ball. What? Even less time in possession? How freakish is this data point going to get?

That, however, is not the story. At least, it’s the story in light of what Graham MacAree notes at Chelsea fan site We Ain’t Got No History. As he’s found out, Opta seems to be miscalculating possession; or, better put, Opta is not reporting a number consistent with the normal expectation for a possession stat.

The normal expectation: When one team has the ball, they’re in possession. I think we can all agree on this, right? This still leaves a lot of gray area. For example, who gets credit for possession when midfield chaos leaves neither side in control? Does one team get possession on a goal kick, when most goal kicks lead to 50-50 midfield challenges? And more broadly, what happens when play is dead but the game clock is running?

I’ve always assumed this is like a chess clock. When one team controls the ball, you hit a button that sends their dials turning. When the other fully regains possession, you hit a button. One clock stops. The other starts running. Those in between moments? They’re governed by one rule: Until possession changes, don’t touch anything.

That, apparently has nothing to do with Opta’s calculations. In fact, Graham’s research suggests Opta doesn’t even run a clock, which may be why they never report possession in terms of time. Instead, the relation between reported possession and total passes suggests Opta just uses passes. As Graham found out, if you take a team’s pass attempts a divide it by the game’s total attempted passes, you have Opta’s possession stat.

What does this mean? Let’s take a totally fake scenario. Barcelona plays three quick passes before trying a through ball that rolls to Petr Cech. It all takes four seconds, while Petr Cech keeps the ball at his feet for eight seconds before picking it up, holding it for five seconds, then putting it out for a throw in, which takes eight more seconds to put back into play.

Despite Barcelona having possession for only four of those 25 fake seconds, they’d have 80 percent of Opta’s possession (three good passes plus one bad, while Chelsea had only Cech’s unsuccessful pass). A logical expectation of a zero-sum possession figure would have that as either 16 percent or (if you credit the time out of play as Barça’s, since they’d have the ensuing throw) 48 percent Barcelona’s. Or, if you do a three-stage model (that’s sometimes reported in Serie A matches), you’d have 16 percent Barcelona, 52 percent Chelsea, and 32 percent limbo/irrelevant.

Of the three methods of reporting possession, Opta’s bares the least resemblance to reality; or, it’s the one that deviates furthest from what we expect from a possession stat.

Ironies being a thing these days, there are two here. First, Opta is the unquestioned leader in soccer data management. How could this happen?

Second, Opta isn’t trying to hide their methods. In fact, they’ve published a post on their site detailing not only their practices but their motivations and research, an investigation that found their approach “came up with exactly the same figures (as time-based methods) on almost every occasion.”

You would think two curmudgeons like Graham and myself would have found this, right? Graham had a reader point it out to him, while a representative from Opta magnanimously pointed me to the piece without the seemingly necessarily indignation of explaining how a Google search works. After all Graham’s work and head scratching – after my lack of work and similar head-scratching – we could have just gone to Opta’s site.

“We try to be as transparent as possible with this stuff,” Opta said when I asked them about it. Certainly, they should be commended being so up front about their methods. After all, they’re a business that makes money off their work. They don’t need to give away their secrets.

But that’s a secondary issue. The main one: Why is a data house like Opta, reputed as the industry standard, taking this short cut? Or, why haven’t they renamed their measure? Granted, the perception that it is a shortcut may have more to do with our expectations than their intent, though based on their defense in the post, it’s clear they do see this as an accurate way of describing possession.

Still, the number they publish is completely redundant to the raw passing numbers also distributed. Why put the measure out at all if not to check a “possession stat” box on a list of deliverables?

Opta’s possession stat shouldn’t be cited in reporting, and if it is, the word “possession” shouldn’t be used to describe it. Reader expectations for anything labeled “possession” are drastically different than what Opta’s producing. The number is confusing to the point of being misleading. It’s becoming counter-information because of its poor packaging.

Even though Opta’s post on the topic is 14 months old, most will be surprised to hear this “news.” It’s disconcerting for anybody who is hoping a SABR-esque revolution’s on the horizon. Almost all of the huge volume of data to which we have access has been useful, but where people are expecting something akin to linear weights to be published tomorrow, we can’t even agree on the terms (let alone the significance of them).

Graham probably puts it better:

I’m completely fine with keeping track of passing volume – I’ve done it before myself. What’s frustrating, from an analyst’s point of view, is that we’re being sold a dud. A statistic that ostensibly measures possession measures something that is not possession, and gets repeated as authoritative anyway.

And people wonder why football statistics don’t get taken very seriously.

Bayern, Germany legend Gerd Muller suffering from Alzheimer’s

JOHANNESBURG, SOUTH AFRICA - JULY  01:  Gerd Muller during a media event discussing the Golden Boot comptetition in the FIFA 2010 World Cup held at the adidas Jo'bulani Central in Sandton Convention Centre on July 1, 2010 in Johannesburg, South Africa. (Photo by Dominic Barnardt/Getty Images for adidas)
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Bayern Munich has confirmed that legendary goalscorer Gerd Muller is suffering from Alzheimer’s.

Muller’s 70th birthday is in November, and the club published a statement that no celebrations would be held due to his ongoing treatment.

One of the greatest strikers to ever play the game, Muller scored 525 goals during his 15-years with Bayern, the most in club history. Karl Heinze-Rummenigge is Bayern’s second leading goalscorer with 218 goals.

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Rummenigge currently serves as the club’s director, and spoke about Muller’s legacy.

Gerd Müller is one of the all-time greats of world football. Without his goals, Bayern Munich and German football would not be what it is today.

There will probably never be another goalscorer like Gerd, yet despite all his successes, he was always very humble and reserved, which particularly impressed me.

He was a fantastic team-mate and is a friend. Gerd will always enjoy a place in the Bayern family.

After he ended his playing career, he brought his experience as a coach of youngsters to the club, helping define the likes of world champions Philipp Lahm, Bastian Schweinsteiger and Thomas Müller, and we are also grateful to him for this.

Muller won the Golden Boot at the 1970 World Cup with ten goals, helping West Germany to a third-place finish. That same year he won the Ballon d’Or as the best player in the world, and helped the West German team capture the European Championship in 1972 and the World Cup in 1974.

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He is one of the top scorers in German national team history with 68 goals, second only to Miroslav Klose’s 71. However, Muller reached 68 goals in just 62 caps, while it took Klose 137 appearances to reach his mark. His 14 World Cup goals are third all-time to Klose (16) and Ronaldo (14).

Watch Live: USA looks to stay perfect against Panama

KANSAS CITY, KS - OCTOBER 01:  The starting lineup from USA poses prior to the 2015 CONCACAF Olympic Qualifying match against Canada at Sporting Park on October 1, 2015 in Kansas City, Kansas.  (Photo by Jamie Squire/Getty Images)
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The United States U-23 team has gotten off to a great start in Olympic qualifying, winning their opening two matches by a combined score of 9-2.

Already into the semifinals, the U.S. faces Panama tonight in Colorado for a chance to stay perfect in Group A play. The U.S. needs a draw or a win to lock up the top spot in the group.

UPDATE: Due to Canada’s 2-2 draw against Cuba, the U.S. has clinched first place in Group A. 

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One of the keys to the United States’ success has been balance, as the team has nine goals from seven different players. Andreas Herzog’s side has also gotten off to quick starts in both matches, as Jordan Morris scored in the opening minute of play in a 3-1 win over Canada. Against Cuba, the U.S. had a 3-0 lead heading into halftime.

You can watch the match live on NBC Universo, or online by clicking the link below.

Group A — USA vs. Panama

When: 9:30 p.m. ET
Where: Dick’s Sporting Goods Park, Commerce City, Colorado
Live Stream: Telemundo