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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.

Gotze’s Bayern future remains uncertain; Sadio Mane still Liverpool’s Plan B?

MUNICH, GERMANY - MAY 14: Mario Goetze of Muenchen celebrates after the Bundesliga match between FC Bayern Muenchen and Hannover 96 at Allianz Arena on May 14, 2016 in Munich, Germany. (Photo by Daniel Kopatsch/Getty Images For MAN)
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Sadio Mane has been an extremely in-demand commodity since last summer, when Manchester United and a handful of other Premier League and foreign clubs failed to pry the Southampton winger away from the South Coast in either one of the summer or January transfer windows.

[ FOLLOW: All of PST’s PL coverage ]

Great players will always be in demand, though, which means another summer full of transfer rumors linking the ever-dangerous 24-year-old to clubs across England and Europe.

Enter stage left: Liverpool manager Jurgen Klopp, who’s eager to undertake his first summer transfer window since taking the Anfield job last October.

[ MORE: Man United confirm Mourinho as new manager ]

Mario Gotze is said to remain Klopp’s no. 1 target this summer — the 23-year-old has said he intends to remain at Bayern Munich and fight for his place under new manager Carlo Ancelotti, but the Bayern hierarchy (Ancelotti included) perhaps see it differently — with Mane a not-so-terrible Plan B should Gotze remain at the Allianz Arena or land elsewhere. Gotze has scored just 22 Bundesliga goals in three seasons at Bayern (36 in all competitions) since making a big-money move from Borussia Dortmund three years ago.

[ MORE: VIDEO — Marcus Rashford scores a debut England goal

After a promising debut in England saw Mane score 10 goals in 30 PL games two seasons ago, the Senegalese dynamo followed up with an 11-goal haul in the PL season just completed (15 goals in all competitions), much of which was shrouded in transfer rumors and clear discontent at St. Mary’s Stadium. Mane will cost anyone a great deal more — think 10 to $15 million more — than the $30 million Bayern hope to recoup in their sale of Gotze (they paid roughly $40 million for him in the summer of 2013).

Pre-EURO int’l friendly roundup: Rooney, Rashford score as England win again

SUNDERLAND, ENGLAND - MAY 27:  Wayne Rooney of England scores his team's second goal of the game during the International Friendly match between England and Australia at Stadium of Light on May 27, 2016 in Sunderland, England.  (Photo by Alex Livesey/Getty Images)
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A roundup of international friendlies as 24 European nations prepare for EURO 2016…

[ MORE: Man United confirm Mourinho as new manager ]

England 2-1 Australia

Roy Hodgson seems to have one of those good dilemmas on his hands: with Danny Welbeck already out for EURO 2016, and Daniel Sturridge injured yet again, does he take 18-year-old Marcus Rashford to France next month? The Manchester United striker is certainly making his case after a breakout finish to the 2015-16 Premier League campaign, which he followed up on Friday with a goal all of three minutes into his England debut (WATCH HERE).

Wayne Rooney doubled England’s lead 10 minutes after he entered the game as a halftime substitute (WATCH HERE), extending the England and Man United captain’s record goal haul to 52 in his international career. Eric Dier scored an embarrassing header to pull one back for the Australians in the 75th minute (WATCH HERE).

England will host Portugal at Wembley Stadium next Thursday in either side’s final pre-EURO friendly.

[ MORE: VIDEO — Marcus Rashford scores another debut goal

Ireland 1-1 Netherlands

The Dutch aren’t headed to EURO 2016 themselves, but the Irish certainly are, and Martin O’Neill’s side picked up a bit of positive momentum in the form of a 1-1 draw with the 2014 World Cup semifinalists.

Southampton’s Shane Long put the Irish ahead when he cleaned up a goal-line scramble on the half-hour mark, but former Newcastle United striker Luuk De Jong turned home a free kick to equalize for the visitors with five minutes remaining in regular time.

[ MORE: Mourinho — “I prefer to forget the last three years at United” ]

Elsewhere in international friendlies

Northern Ireland 3-0 Belarus
Croatia 1-0 Moldova
Czech Republic 6-0 Malta
Slovakia 3-1 Georgia

Former NBA exec named CONCACAF’s new secretary general

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MIAMI (AP) CONCACAF has appointed former NBA executive Philippe Moggio as its general secretary.

[ COPA AMERICA PREVIEWS: Group A | BC | D ]

The Confederation of North, Central America and Caribbean Association Football said Moggio will take his position June 13.

Moggio previously served as senior vice president and managing director of Latin America and the Caribbean for the NBA.

[ MORE: Preview — USMNT faces Bolivia in final Copa America tune-up ]

As CONCACAF general secretary, Moggio will be in charge of the organization’s daily business and operations. He succeeds Ted Howard, who has served in the role since last May.

CONCACAF has undergone changes in its governing structure since the sport’s global corruption scandal hit.

VIDEO: Man United’s Marcus Rashford scores 3 minutes into his England debut

NEWCASTLE UPON TYNE, ENGLAND - MAY 26:  Marcus Rashford of England arrives at the team hotel on the eve of their international friendly against Australia at the Hilton Gateshead on May 26, 2016 in Newcastle upon Tyne, England.  (Photo by Stu Forster/Getty Images)
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12 months ago Nine months ago Six months ago Three months ago, if anyone asked you, “who is Marcus Rashford?” you, just like me, probably would have responded as such: “I haven’t a clue. Should I know who he is?”

[ MORE: Man United confirm Mourinho as new manager ]

Stars are, of course, born overnight in the sports world, and the 18-year-old Manchester United striker, who spent 12 years with the club’s youth academy, is just the latest example. On Feb. 25, he made his first-team debut and scored twice in the Europa League. Three days later, he made his Premier League debut, again scoring twice.

[ MORE: Mourinho — “I prefer to forget the last three years at United” ]

Fast forward to Friday, and Rashford is a fully-fledged England international. In keeping up with the theme of his other debuts this season, he marked his international debut with a goal against Australia after just three minutes of play at the Stadium of Light.

It remains to be seen whether Rashford completes his hat trick of debut braces this year. We’ll update this post if he does so.