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.

CONMEBOL WCQ: Venezuela, Bolivia teetering on elimination

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CONMEBOL World Cup qualifying is always a challenge, and this World Cup cycle is no different.

With six teams currently separated by a mere five points under leaders Brazil, everything is left to play for as Round 14 hits South America.

[ MORE: Messi could face suspension from CONMEBOL ]

Here’s a look at what’s on the docket for Tuesday:

Bolivia vs. Argentina — 4 p.m. EDT

It wasn’t pretty at all, but La Albiceleste picked up a crucial three points against Chile, which could produce a morale lift for Argentina given their past struggles against the reigning Copa America holders.

Lionel Messi’s actions from the match could harm the Albiceleste though, with the Barcelona man reportedly facing sanctions from CONMEBOL for verbally abusing a linesman.

Meanwhile, Bolivia is in desperate need of a win in La Paz, and anything but three points could potentially end La Verde’s hopes of reaching Russia 2018.

Ecuador vs. Colombia — 5 p.m. EDT

It took a long time for Colombia to crack the Bolivia backline on Thursday but a late run from Juan Cuadrado helped set up the eventual winner from James Rodriguez, and kept Los Cafeteros in the top four.

Ecuador didn’t have the same fortunes though four days ago after falling to a very game Paraguay side. La Tricolor have gone winless in three of its last four World Cup qualifiers, leaving Gustavo Quinteros side with little margin of error against the Colombians.

Chile vs. Venezuela — 6 p.m. EDT

Chile’s qualifying struggles continued on Thursday after falling to La Albiceleste in a closely-contested match. Arturo Vidal’s six goals leave the Bayern Munich midfielder third in all of CONMEBOL this campaign, but the Chileans still sit on the outside looking in at the moment and in sixth place.

Venezuela is teetering on the edge of elimination, and a loss against Chile would all but seal their fate of missing out the World Cup. After reaching the quarterfinals at last summer’s Copa America Centenario, La Vinotinto have failed to replicate that form this qualifying campaign with just one win to show.

Top scorer Josef Martinez is no longer with Venezuela after suffering an injury in Thursday’s 2-2 draw against Peru, creating a major void in the side’s attack.

Brazil vs. Paraguay — 8:45 p.m. EDT

The Selecao continue to score at a lightning pace this qualifying campaign with 32 goals in the first 13 rounds of play. Despite conceding early to Uruguay on Thursday, Brazil responded emphatically with four goals, and most notably Paulinho‘s hat-trick.

Elsewhere, Paraguay kept itself within striking distance of the top five after its 2-1 win over Ecuador. The side is just two points behind fifth place Ecuador.

Peru vs. Uruguay — 10:15 p.m. EDT

Los Incas have not reached a World Cup since 1982, and although the team is just five points behind fifth, they need to pick up victories. Ricardo Gareca will be pleased with his side’s resiliency against Venezuela on Thursday, but more draws simply won’t do with only four rounds remaining after Tuesday.

Uruguay still sits in a solid second position after Thursday’s slip up against Brazil but another defeat could be potentially disastrous for La Celeste, who are just three points above sixth place Chile. However, Edinson Cavani’s nine goals leads all of CONMEBOL and Peru has allowed the third-most goals this campaign (22).

Ugly scene forces Ivory Coast-Senegal match to be abandoned

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Monday’s international friendly between Ivory Coast and Senegal turned out to be anything but that when the match was interrupted towards the tail end.

Photo by Dan Mullan/Getty Images)

The fixture was abandoned with two minutes remaining in regulation after pitch invaders disrupted the the match by getting past security guards and began chasing after players from both sides.

The score was level at 1-1 in the 88th minute when the disruptions occurred, causing the referee to halt play at the Stade Sebastien Charlety in Paris.

One of the intruders even managed to tackle Senegalese defender Lamine Gassama (as shown in the picture to the right).

Liverpool’s Sadio Mane gave Senegal the lead minutes into the second stanza after he converted from the penalty spot, while Cyriac Gohi Bi leveled the score at one apiece just minutes later.

Messi could face CONMEBOL suspension for verbal abusing official

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Already facing some uncertainty with a depleted roster, Argentina could face a significantly greater challenge.

[ MORE: Aguero left out of Argentina starting XI vs. Bolivia ]

Barcelona star Lionel Messi could face suspension after reportedly verbally abusing linesman Marcelo Van Gasse during the second half of Thursday’s 1-0 win over Chile.

UPDATED: Fox Sports Argentina is reporting that Messi will receive a two to four match suspension and will be effective for tomorrow’s match against Bolivia.

Messi was reported to CONMEBOL for yelling, “F*** off, your mother’s c***” at Van Gasse and refused to shake the official’s hand at the end of the match.

The officiating crew from the match didn’t initially include Messi’s rant in the post-match report, however, it was added on Monday and submitted to CONMEBOL.

The South American federation must now decide if and when it will punish Messi for his reported actions, and there is the potential that the world-class attacker could be suspended for Tuesday’s clash against Bolivia if the federation acts quickly.

There are several other scenarios though for CONMEBOL to action, including disregarding Messi’s verbal assault.

La Albiceleste currently sit third in World Cup qualifying on 22 points.

Arena speaks about USMNT turnaround, says “no secret formulas”

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It’s only been one competitive match since Bruce Arena regained control of the U.S. Men’s National Team and there’s already been a noticeable difference in form.

[ MORE: Three keys for the USMNT ahead of Panama clash ]

The former LA Galaxy manager wouldn’t have you believe that though following Friday night’s convincing 6-0 victory over Honduras in CONCACAF World Cup qualifying.

“It’s nothing I can write a book on,” Arena said about his team’s turnaround in form against Honduras. “You have a sense of your group, and you go about doing your business. There’s no secret formulas to this stuff. Work together, take ownership in what you’re doing, treat them like responsible professional athletes, and you get on with your business.

He added, “They want to be successful. They want to play in a World Cup. Is that a recipe for success? I don’t know. I’m sure Honduras wants to play in a World Cup too.”

Arena, who took over for Jurgen Klinsmann following the U.S.’ collapse during the first two matches of the Hexagonal, is unbeaten in his first three games in charge since getting his job back with the Stars and Stripes.

Although there has been a considerable turnaround in the way the USMNT has performed in the first three matches of 2017, Arena wouldn’t stoop to comparing his style to that of Klinsmann.

“I’m not doing anything differently,” he said. “I’m not taking a survey [of the players]. I know it’s different. We lose tomorrow, there will be articles written that, ‘This a—— is letting these guys run loose.'”

“I have spent no time on the past. There’s nothing I can do about it. I kind of have a sense about things, but there’s no point in me spending time investigating what went on in the past. The idea was to get it going the right way from the start.”

Arena’s next test with the U.S. will be on Tuesday when the Yanks travel to Panama City to take on Panama.