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

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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.

Barcelona invites Chapecoense to play friendly

CHAPECO, BRAZIL - OCTOBER 22: Supporters of Chapecoense cheer their team during the match between Chapecoense and Sao Paulo for the Brazilian Series A 2014 at Arena Conda on October 22, 2014 in Chapeco, Brazil. (Photo by Alan Pedro/Getty Images)
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BARCELONA, Spain (AP) Barcelona says it has extended an invitation to host a friendly match against the Brazilian soccer club involved in last week’s plane crash.

Chapecoense was on its way to the final of the Copa Sudamericana, one of South America’s most prestigious club tournaments, when its flight went down in Colombia, killing all but six of the 77 players, officials and journalists on board.

The match would be played in August. The friendly, called the Joan Gamper trophy, is used as Barcelona’s traditional curtain raiser for the new season.

Barcelona says it sent a formal invitation to Chapecoense on Thursday.

Barcelona says it wants to “pay homage to the 71 people who died in the accident as well as their families.”

Wenger discusses future of Sanchez, Ozil at Arsenal

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With just 18 months left on their current contracts, the futures of both Alexis Sanchez and Mesut Ozil at Arsenal is becoming a daily topic.

[ MORE: Ranking the PL superstars ]

This week alone Sanchez has been linked with a move to China on Wednesday, plus Real Madrid and Chelsea on Thursday, while another report from the Telegraph suggest the Gunners are willing to listen to offers for 28-year-old Ozil who isn’t willing to back down on his hopes of getting a $487,000 week contract at Arsenal where he is currently the top earner on $180,000.

To try and clear up any of the speculation Arsenal’s manager Arsene Wenger, who only has a contract at the Emirates until the end of the current season, has been speaking to the media about the reports.

Asked if Arsenal was willing to break their transfer structure, he said they’ll “do the maximum of what we can for every single player” to remain at the club.

He then reinforced the notion that Sanchez and Ozil would remain at Arsenal for at least 18 months, and hopefully much longer.

“Eighteen months is quite long in football. They have 18 months on their contracts and are completely committed to do well as long as they are here,” Wenger said. “Beyond that we will try to extend their contracts but I can’t make that a subject of every press conference as that is normal. These players have 18 months, they will be staying 18 months and hopefully much longer. I don’t believe that it is a problem.”

“A contract is between two parties and on my side the best position is to achieve it early. You have to accept that negotiations are private and secret and we don’t have to explain what we do with negotiations.”

Asked about the astronomical sums of cash reportedly being offered to Sanchez to go and play in the Chinese Super League — reports state the Chilean star has offers of $505,000 per week on the table — Wenger believed it was true but questioned why either would leave England.

“Why should you go to China when you are playing in England? We live in a world where the great players like Alexis Sanchez and Mesut Ozil earn a lot of money and have the privilege to choose where they want to play,” Wenger said. “The commitment of Alexis Sanchez and Mesut Ozil is absolute total and I’m very pleased with that. We are professionals and the first quality is to give 100 percent, it is here and now, that is what it means to be professional and to be fully committed to the cause.”

So, Wenger is confident the superstar duo will stay. Should he be?

With Paul Pogba earning over $368,000 as the current top earner in the Premier League, it’s easy to see why Ozil and Sanchez believe they’re worth more than Pogba is currently earning at Manchester United.

Sanchez, 27, has been ripping it up this season, scoring 11 times in 14 PL outings and Ozil has already matched his goal tally from last season with eight strikes in all competitions.

Arsenal’s wage structure is said to be set at $250,000 per week, with an insistence on no player earning more than Wenger does.

Unless they change that stance it’s difficult to see how Sanchez and Ozil will remain at the Emirates Stadium with so many suitors from across the Premier League, Europe and worldwide willing to double, or even treble, their current wages.

Of course the Premier League is the most-watched in the world and there are many advantages to playing in it for Sanchez, Ozil and other superstars but money talks. If these huge offers from the Chinese Super League are true, why wouldn’t players move there to cash in on their relatively short playing careers?

MLS Cup: Toronto FC all about the team

Toronto FC defender Nick Hagglund, center, celebrates his goal against the Montreal Impact with teammates Michael Bradley, right, and Steven Beitashour (33) during the second half of the second leg of MLS Eastern Conference championship series, in Toronto on Wednesday, Nov. 30, 2016. (Frank Gunn/The Canadian Press via AP)
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Toronto, Ontario (AP) Team has been the theme for Toronto FC in the buildup to the MLS Cup final.

From boisterous practices to team-first media interviews, the All for One club motto has been plain to see ahead of the championship game Saturday against the visiting Seattle Sounders.

“You don’t get to this point by mistake or by accident. You get here because a group of special guys who have all bought into a philosophy, an identity,” said Toronto midfielder Will Johnson, an MLS Cup winner with Real Salt Lake and Portland.

“I say the same about Seattle. They’re bought into what they’re good at. We’re bought in, very motivated and want to sacrifice and put aside egos to get to a point as a team to compete for the big trophy.”

[ MORE: Designing the best UCL Round of 16 ]

Star striker Jozy Altidore, no fan of chatting with the media, was downright prickly when a reporter asked him if he had taken time to reflect on his personal journey to the championship game.

“No,” he said definitively. “This isn’t personal, this is a team game. We’re here to try to help Toronto to be a winning team. This has nothing to do with individuals. So it has nothing to do with what I’ve been through. This is what the city’s been through, what the fans have been through, what this club has been through. That’s far more important.”

Fullback Justin Morrow, a seven-year MLS veteran, has never played this deep into the season before.

“Each week we build on top of each other and we get closer as the year goes on. It really feels like it’s a culmination this week,” he said.

[ UCL: Who can Arsenal, Man City, Leicester draw? ]

Coach Greg Vanney has made a point of praising the entire squad, including reserves who function as the scout team in practice. While he has done soccer’s equivalent of shortening his bench for the playoffs, the squad has stayed on point. If anyone has beefs, they have been kept to themselves.

That’s no small feat considering the salaries on the squad range from $7.12 million for star striker Sebastian Giovinco to $51,500 for youngsters Mo Babouli and Tsubasa Endoh.

For Morrow, being part of a tight-knit group allows you to forget that it is your job.

“When teams aren’t doing well, players tend to focus on that – their job and not about the other people on the team,” Morrow said. “And I think when teams are doing well, it becomes about the relationships between the players.”

Report: Atlanta United to acquire Parkhurst; Guardado hopes fading

COLUMBUS, OH - MARCH 12:  Michael Parkhurst #4 of the Columbus Crew SC controls the ball against against the Philadelphia Union on March 12, 2016 at MAPFRE Stadium in Columbus, Ohio.  (Photo by Jamie Sabau/Getty Images)
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Atlanta United is adding MLS experience to its high-flying international acquisitions.

The expansion side is set to acquire Michael Parkhurst from the Columbus Crew, according to a report from The Sporting News.

[ MORE: Mourinho worried about Zorya pitch ]

Parkhurst, 32, has been a fixture for the Crew since returning to MLS after stints with Nordsjælland and FC Augsburg. The 25-times capped American defender would join a relatively loaded expansion unit that reportedly will also add veteran Chicago goalkeeper Sean Johnson.

Unfortunately for Atlanta, it seems the first-year club’s hopes of landing Mexican star Andres Guardado are fading.

From Ives Galarcep for The Sporting News:

The club has one remaining designated player slot it is expected to fill ahead of its inaugural 2017 season, but transfer target Andres Guardado appears less likely to be the player to fill that slot, sources have told Goal USA.

The Crew was a massive disappointment last season, failing to make the playoffs one season after making a run to the MLS Cup Final. Is Parkhurst a good gamble for Atlanta?

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