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.

La Liga: Real Madrid shocked by Mallorca; Messi, Suarez, Griezmann send Barca top

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A roundup of all of Saturday’s action in Spain’s top flight…

[ MORE: Lampard “pleased for Pulisic,” praises subs in Chelsea win ]

Eibar 0-3 Barcelona

Lionel Messi goal – check; Luis Suarez goal – check; Antoine Griezmann goal – check; clean sheet – check. If there exists a perfect recipe for a Barcelona victory this season, the Blaugrana put it to good use en route to a fourth straight La Liga victory and top spot in the league table on Saturday.

Griezmann opened the scoring in the 13th minute, followed by Messi in the 58th and Suarez in the 66th. Marc-Andre ter Stegen didn’t have to make a single save as Eibar managed just five shots in the game.

Mallorca 1-0 Real Madrid

Real Madrid’s unbeaten start to the season was snapped at eight games on Saturday, when Los Blancos went to Mallorca and suffered a hugely underwhelming 1-0 defeat. Zinedine Zidane’s side — already without the likes of Gareth Bale (calf), Luka Modric (bruise), Toni Kroos (adductor) and Marco Ascensio (knee), among others — finished the game with 10 men after Alvaro Odriozola earned his second yellow card in the 74th minute. The defeat sees Madrid fall off the top spot, now sitting second behind Barca.

Lago Junior scored the game’s only goal in the 7th minute and Mallorca held on for 83 more, allowing just four shots on target (12 in total). The early goal was Mallorca’s only shot on target over 90 minutes.

Atletico Madrid 1-1 Valencia

Atleti coughed up a late lead and settled for a 1-1 draw with Valencia, but the worst news of the day comes in the form of an injury suffered by Joao Felix. The 19-year-old’s ankle buckled underneath him late in the second half. Atleti finished with 10 men after their $140-million superstar was forced off.

Elsewhere in La Liga

Getafe 2-0 Leganes

Sunday’s La Liga schedule

Alaves v. Celta Vigo — 6 a.m. ET
Real Sociedad v. Real Betis — 8 a.m. ET
Espanyol v. Villarreal — 10 a.m. ET
Athletic Bilbao v. Real Valladolid — 12:30 p.m. ET
Sevilla v. Levante — 3 p.m. ET

Haringey Borough abandon FA Cup qualifier after racist abuse

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LONDON (AP) An FA Cup qualifier between Haringey Borough and Yeovil Town was abandoned Saturday when the home team walked off the field after one of its players was racially abused.

[ MORE: Analyzing a day of VAR drama in the Premier League ]

Haringey, a London-based non-league club, walked off in the 64th minute after claims its Cameroonian goalkeeper Valery Pajetat had been targeted by racial abuse by visiting fans minutes earlier, when Yeovil took a 1-0 lead from a penalty.

Haringey manager Tom Loizou told BBC Radio 5 Live that defender Coby Rowe was also racially abused, and that “there was no way I could let him continue.”

The match at Coles Park Stadium was in the fourth qualifying round for the FA Cup, with the winner advancing to the first round of the tournament.

[ MORE: Lampard “pleased for Pulisic,” praises subs in Chelsea win ]

“The abuse a few of my players got was disgusting,” Loizou said. “Yeovil’s players and manager were different class. Their team tried to calm their supporters down, they tried their best and they supported us. They said, ‘If you’re walking off, we’re walking off with you.’ I took the decision to take my team off and I don’t want Yeovil Town to get punished for it. If we get thrown out of the FA Cup and they go through, there is no hard feelings there.”

The incident comes four days after England’s European Championship qualifier in Bulgaria was stopped twice in the first half as home fans hurled racial abuse at England’s black players. However, England decided to play on and won 6-0.

In a statement on Twitter, the football anti-discrimination charity Kick It Out praised the “swift and decisive action” taken by the Haringey manager Tom Loizou and his players.

Bundesliga wrap: Dortmund beats leaders Gladbach; Bayern draws

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Another Saturday in the Bundesliga, another nutty set of results allowing a side the chance to claim the top of the league on Sunday.

David Wagner, Weston McKennie and Schalke are the ones licking their lips this time, knowing that a win at Hoffenheim will boost them into first.

[ MORE: Lampard “pleased” for Pulisic ]

Wolfsburg remains unbeaten with a draw, and dropped points for Borussia Monchengladbach, RB Leipzig, and Bayern Munich means an absurd nine teams are within two points of the top of the table.

Nine!

Borussia Dortmund 1-0 Borussia Monchengladbach

Gladbach’s stay atop the league could last just one match day, as Thorgan Hazard set up Marco Reus for a 58th minute goal and a place one point back of the top.

Werder Bremen 1-1 Hertha Berlin

Josh Sargent’s 7th minute goal didn’t stand up, thanks to Hertha’s electric Dodi Lukebakio scoring with 20 minutes to play. Watch the American striker’s goal, here.

Augsburg 2-2 Bayern Munich

The champions’ stumbles continued, with first minute concession providing a test. Bayern’s red hot pair delivered a lead, with Robert Lewandowski answering in the 14th minute, and Serge Gnabry supplying a 49th minute lead.

Stoppage time was the downfall, though, as Alfred Finnbogason helped himself to the equalizer with all kinds of questions for the Bayern defense.

Elsewhere

Eintracht Frankfurt 3-0 Bayer Leverkusen — Friday
Union Berlin 2-0 Freiburg
Fortuna Dusseldorf 1-0 Mainz
RB Leipzig 1-1 Wolfsburg
Koln v. Paderborn — 9:30 a.m. ET Sunday
Hoffenheim v. Schalke — Noon ET Sunday

STANDINGS

Team GP W D L GF GA GD Home Away PTS
 Mönchengladbach 8 5 1 2 15 7 8 2-1-1 3-0-1 16
 VfL Wolfsburg 8 4 4 0 11 5 6 2-2-0 2-2-0 16
 Bayern Munich 8 4 3 1 22 10 12 2-1-1 2-2-0 15
 Borussia Dortmund 8 4 3 1 20 11 9 3-1-0 1-2-1 15
 RB Leipzig 8 4 3 1 16 8 8 1-2-1 3-1-0 15
 FC Schalke 04 7 4 2 1 14 7 7 2-1-1 2-1-0 14
 SC Freiburg 8 4 2 2 15 9 6 1-2-1 3-0-1 14
 Eintracht Frankfurt 8 4 2 2 14 10 4 3-2-0 1-0-2 14
 Bayer Leverkusen 8 4 2 2 12 11 1 2-2-0 2-0-2 14
 Hertha BSC Berlin 8 3 2 3 13 13 0 2-0-1 1-2-2 11
 Werder Bremen 8 2 3 3 13 17 -4 1-1-2 1-2-1 9
 1899 Hoffenheim 7 2 2 3 6 11 -5 1-0-2 1-2-1 8
 Fortuna Düsseldorf 8 2 1 5 10 14 -4 1-1-2 1-0-3 7
 1. FC Union Berlin 8 2 1 5 8 13 -5 2-0-3 0-1-2 7
 FC Augsburg 8 1 3 4 10 21 -11 1-2-1 0-1-3 6
 FSV Mainz 05 8 2 0 6 7 18 -11 1-0-2 1-0-4 6
 1. FC Köln 7 1 1 5 5 16 -11 0-0-3 1-1-2 4
 SC Paderborn 7 0 1 6 9 19 -10 0-0-4 0-1-2 1

Brilliant Barco assist helps Atlanta outlast New England

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The game in 200 words (or less): Highly-favored at home, the reigning champions needed their goalkeeper to keep them alive against a New England Revolution side that only made the postseason via MLS’ decision to let almost everyone make it. Yes, Atlanta United dodged a bullet as Brad Guzan made six saves and Ezequiel Barco’s slick pass set up Franco Escobar for a brilliant winner with about 20 minutes to play. New England fought to the very death, but couldn’t take advantage of the absence of Miles Robinson.

[ MORE: Lampard “pleased” for Pulisic ]

Soon-to-retire Michael Parkhurst appeared to dislocate his shoulder late in a challenge with Cristian Penilla, and needed a lot of help to get off the field. Hopefully that wasn’t the last we see of him.

Atlanta will host either Philadelphia or the New York Red Bulls on Thursday evening.

Three things we learned

1. Guzan overcomes blip to stand tall: The longtime USMNT backup made a major error and nearly allowed New England in front but was otherwise sensational over 90 minutes in Georgia.

2. Martinez off, and Martinez off: While Frank De Boer opted to keep Gonzalo “Pity” Martinez out of the Starting XI, it was his star striker who nearly made him pay for the decision. Josef Martinez was not on his game, and lashed a should-be winner from his office over the goal in the first half before being stopped on by Turner on a 1v1 as the match neared stoppage time.

3. Barco makes the difference: Who knows if the 20-year-old Argentine will ever fully deliver on his promise, but the plays he made to set up Escobar’s goal was sensational. After dancing around a pair of defenders, he cut a shot pass between two defenders for the on-running Escobar to blast past Matt Turner.

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Man of the match: Barco

Goalscorers: Escobar (70′)