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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.

Watch Live: Swansea City vs. Liverpool (Lineups & Live Stream)

during the Barclays Premier League match between Liverpool and Swansea City at Anfield on November 29, 2015 in Liverpool, England.
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Liverpool continues to fight for a top 7 spot as it takes on 15th placed Swansea at the Liberty Stadium live at 7 a.m. ET on NBCSN or live online via NBC Sports Live Extra.

The Reds need a result to ensure themselves a place in European play next year. They’re still in the competition and could make the Champions League by winning the competition, but down 1-0 to Villareal after the first leg of the semifinals midweek, that is by no means a sure thing.

WATCH LIVE: Swansea City vs. Liverpool live online via NBC Sports Live Extra

Despite that, Jurgen Klopp has rested a number of regulars, including goalkeeper Simon Mignolet, replaced by Danny Ward in the youngest-ever starting lineup for Liverpool in the Premier League. One man not rested is Daniel Sturridge starts up front for the Reds.

For Swansea, who sits eight points above the drop on the magic 40-point mark, Andre Ayew starts at the head of the attack, supported by Jefferson Montero, who’s beginning to receive more time after spending all of January and February stuck to the bench.

LINEUPS

Swansea City: Fabianski, Rangel, Amat, Williams, Taylor, Britton, Cork, Sigurdsson, Routledge, Montero, Ayew.
Subs: 
Nordfeldt, Naughton, Fernandez, Ki, Fulton, Barrow, Gomis.

Liverpool: Ward, Clyne, Skrtel, Lovren, Smith, Stewart, Chirivella, Ibe, Ojo, Coutinho, Sturridge.
Subs: 
Mignolet, Benteke, Lallana, Lucas, Brannagan, Teixeira.

MLS Snapshot: Real Salt Lake 2-1 Houston Dynamo (video)

Real Salt Lake goalkeeper Nick Rimando shouts during the second half of an MLS soccer match against the Seattle Sounders Saturday, Aug. 22, 2015, in Sandy, Utah. Real Salt Lake won 2-0. (AP Photo/Rick Bowmer)
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The game in 100 words (or less): Real Salt Lake are tied (with the Colorado Rapids and FC Dallas) for the top spot in the Western Conference and in the race for the Supporters’ Shield (with one and two fewer games played, respectively) following 2-1 come-from-behind victory over the bottom-of-the-league Houston Dynamo at Rio Tinto Stadium on Saturday. Jordan Allen and Yura Movsisyan bagged the goals for RSL, not long after Miranda gave the visitors the game’s first lead nine minutes after halftime. The lasting image of Saturday’s game, as seems to have been the case on about 100 prior occasions, was the late heroics of goalkeeper Nick Rimando (below video).

[ MORE: Monday’s MLS Rewind column  ]

Three Four Five moments that mattered

15′ — Willis denies Burrito not once, but twice — Joe Willis just would not be beaten by Juan Manuel “El Burrito” Martinez.

54′ — Miranda uses the deflection for the opener — Credit Jamison Olave for the deflection if you must, but failing to deal with the initial ball into the box, followed by Nick Rimando spillage were just as at fault.

62′ — Allen fires past Willis for the equalizer — Likewise, turning the ball over five yards outside your own penalty area is inadvisable. The pass (Justen Glad) and finish (Allen) were clinical.

70′ — Movsisyan turns home the near-post cross — Demar Phillips provided the pinpoint cross, and Movsisyan made no mistake on the finish for a 2-1 lead. This is pretty soccer.

80′ — Rimando’s (double-)Save of the Year candidate — Never retire, Nick . Never, ever, ever, please.

[ FOLLOW: All of PST’s MLS coverageStandings | Stats | Schedule ]

Man of the match: Nick Rimando

Goalscorers: Miranda (54′), Allen (62′), Movsisyan (70′)

MLS Snapshot: New England Revolution 2-2 Orlando City SC (video)

New England Revolution forward Diego Fagundez, right, congratulates forward Juan Agudelo (17) after he scored against Orlando City during the second half of an MLS soccer match Saturday, Sept. 5, 2015, in Foxborough, Mass. The Revolution won 3-0. (AP Photo/Stephan Savoia
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The game in 100 words (or less): The New England Revolution and Orlando City SC love a 2-2 draw with each other, don’t they? Two weeks after a 2-2 stalemate at the Citrus Bowl, the two sides split four more goals between them on Saturday at Gillette Stadium. Juan Agudelo came off the bench with the game tied 1-1, 70 minutes on the clock, and scored what the Revolution believed to be the winning goal, if not for Carlos Rivas’s 90th-minute equalizer. Le Nguyen bagged a pair of assists on the day, and it’s little surprise that just as he’s getting things going for the season, the Revs have picked up at least a point in five of their last six games. The draw moves the Revs (10 points) up two spots in the Eastern Conference, to seventh, while the Lions started the day in seventh and finish in fourth.

[ MORE: Monday’s MLS Rewind column  ]

Three Four Five moments that mattered

7′ — Fagundez roofs it for the opener — Lee Nguyen and Diego Fagundez working a one-two inside your penalty area is the last thing you want to see if you’re an opposing goalkeeper. They did it to perfection here, and the Revs had an early lead.

20′ — Revs come up empty in the scramble of all scrambles — How in the world did the ball not find the back of the net here? Unbelievable.

30′ — Molino slots home at the back post for 1-1 — Molino is catching a bit of fire of late, with three goals in his last five games, after missing most of last season with a torn ACL. Right place, right time on this one.

71′ — Agudelo slots home from a cross for 2-1 — Agudelo is finally on the board for 2016, about a month and a half later than you’d have hoped. When he’s on, he’s on and he makes it look so easy.

90′ — Rivas pokes it home in the face of goal — Cyle Larin is usually on the other end of crosses into the box, but the big Canadian showed a surprising combination of speed and chance-creating ability in setting Rivas up for the late equalizer.

[ FOLLOW: All of PST’s MLS coverageStandings | Stats | Schedule ]

Man of the match: Lee Nguyen

Goalscorers: Fagundez (7′), Molino (30′), Agudelo (71′), Rivas (90′)

Worker dies after falling ill at Qatar World Cup stadium site

In this photo taken during a government organized media tour, workers use heavy machinery at the Al-Wakra Stadium being built for the 2022 World Cup, in Doha, Qatar, Monday, May 4, 2015. Qatar’s inability to ensure decent housing for its bulging migrant labor population was “a mistake” the government is working to fix as it prepares to host the 2022 World Cup, the country’s top labor official said Monday, vowing his country would improve conditions for its vast foreign labor force. (AP Photo/Maya Alleruzzo)
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DOHA, Qatar (AP) World Cup organizers say a worker has died after falling ill on the site of one of the stadiums being constructed for the 2022 tournament in Qatar.

[ MORE: The latest FIFA news ]

The Supreme Committee for Delivery and Legacy said Saturday that 48-year-old Indian national Jaleshwar Prasad died after he “fell ill on-site around 9:30 a.m. on Wednesday.”

The statement says that Prasad, who was a steel worker employed on the Al Bayt Stadium project, “received first aid treatment until paramedics arrived. He was transferred to Al Khor Hospital but sadly passed away around 11:30 a.m. Al Khor Hospital reported the cause of death as cardiac arrest.”

It adds that “a full investigation is underway.”

[ MORE: FIFA panel to monitor labor conditions in Qatar ]

Qatar is often criticized by rights groups and trade unions for alleged abuses and deaths on a range of construction projects linked to the 2022 World Cup since it won hosting rights in 2010.

Qatar is relying heavily on construction workers from south Asia.

A FIFA-appointed human rights expert from Harvard University recently advised that tournaments should be moved from countries where abuses persisted.