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.

Pique with the scoop? Neymar “staying” at Barcelona

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While the entire world waits for official word — any word, really — on the possible world record-shattering transfer of Neymar from Barcelona to Paris Saint-Germain, Gerard Pique just became the world’s most appreciated breaker of transfer news.

[ MORE: Sunday’s transfer rumor roundup | Saturday | Friday ]

Pique, Neymar’s teammate for four seasons at Barca, tweeted (and posted to Instagram) a photo of himself and Neymar, captioned, “Se queda,” or, “He stays.”

[ MOURINHO: United not signing Bale | De Gea not going anywhere ]

Whether he stays or goes this summer, Neymar is about to get paid, and deservedly so. An unquestionable top-five (or -three?) player in the world, he doesn’t turn 26 for another seven months. There has to be someone awaiting the passing of the torch from Lionel Messi and Luis Suarez, both four years Neymar’s senior, some day soon(-ish), so it should come as no surprise that Barca appear to have moved heaven and earth to retain their Brazilian superstar.

Mourinho “guarantees” De Gea won’t go to Real Madrid

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Jose Mourinho has always said what he wants, when he wants, how he wants — especially when he’s working an ulterior motive.

[ MORE: Sunday’s transfer rumor roundup | Saturday | Friday ]

Example no. 6,394: the Manchester United manager’s comments regarding the future of goalkeeper David De Gea, who has long been linked with a move to Real Madrid, which just so happens to be one of Mourinho’s former employers. Long story short, “It ain’t happening” — quotes from the Guardian:

“I can guarantee that he’s not going this season, that I can, and my feeling is it will be very difficult for him to go. Because he’s a very honest boy, very straight.”

“He was contacted for a long time [by Real]. The club was close, then we open because I always have this feeling of when a player has a desire to go I don’t like to stop players to go because in the end you don’t get what you expect from them if they want to move and they don’t.

“I don’t think the feeling from him [towards Real] is very good. I see him very happy and focused and working better than ever so for me 100% he stays with us.”

[ MORE: Man City make a dream come true… for $35 million ]

De Gea has two years remaining on his current contract (with an option for one more), which he signed shortly after United and Madrid’s deadline-day debacle of 2015.

Roma’s Moreno happy as Mexican ambassador to Serie A

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Hector Moreno knows his move to AS Roma is a big deal for him, his club, and his country.

That may seem like a bit too much aggrandization, but Moreno joins the biggest club of his accomplished European career. That club nearly ended the scudetto reign of Juventus last season, coming as close as anyone in recent history.

And he’s the first Mexican to play for Roma, a club a bit higher in the pecking order than the homes for previous El Tri members in Serie A (Carlos Salcedo went on loan to Fiorentina last season, while Miguel Layun spent time at Atalanta and Rafa Marquez played three seasons at Verona).

[ MORE: Strootman loving life at Roma ]

“I know what people expect from me, and the people in Italy will look back at Mexico as a place to find good players if I do well,” Moreno told ProSoccerTalk ahead of the club’s second Stateside match of the International Champions Cup, Tuesday versus Tottenham Hotspur at Red Bull Arena.

“Football in Mexico is lived with so much passion. It’s so important.”

What they’ve seen from the 29-year-old center back gives them every reason to be proud. Moreno has won the Eredivisie with two clubs (AZ Alkmaar and PSV Eindhoven) and was Espanyol’s Player of the Year during his first of three campaigns in La Liga.

Moreno’s offensive acumen shone through his second stint in Holland, and the center back who also plays some left back scored seven goals last season.

(Photo by Duane Burleson/Getty Images)

When Roma came calling, he had little hesitation.

“It’s something I have wanted my entire career, for an opportunity like this,” Moreno said. “It’s an amazing challenge to keep going forward in my career.”

Moreno captained El Tri in a 1-1 draw against the United States in World Cup qualifying on June 12, and the Roma signing was announced on June 13. Five days later, he was pushing Mexico over the line with a stoppage time goal against Portugal at the Confederations Cup.

[ MORE: Pallotta’s Roman vision ]

Again, this was about a statement for both him and his country, especially with Mexico in pole position to finish first in CONCACAF World Cup qualification and the desire to make it past the Round of 16 for the first time in seven tournaments.

“It was a great moment and the feeling was amazing because we fought so hard and we didn’t expect to lose,” Moreno said. “It looks easy to say but with Ronaldo, Ledesma, Pepe, at the end we got a result that we deserved.

“And this will probably help the team to know where we stand because in CONCACAF qualification for World Cup we are almost there and in all due respect it’s a different quality of play than CONCACAF. You can see where you stand and what you have to improve to be on the level. It is the dream forever that we can go to the fifth game, and we can do that in Russia. We’re going to work hard and I hope we can make it.”

[ MORE: Conte names Gary Cahill new Chelsea captain ]

It may surprise some to hear that Moreno also hopes El Tri’s heated rivals in the U.S. qualify for Russia as well.

“I hope so,” Moreno quickly replies. “It would make a good tournament. They always make it through and they have such a good team. It’s always (the hope) that Mexico and U.S. can meet in the World Cup, because they have such good talent as well.”

Roma faces Spurs in New Jersey on Tuesday before a July 30 battle with Juventus at Gillette Stadium in Foxborough.

What’s another $35 million? Man City sign Danilo from Real Madrid

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MANCHESTER, England (AP) Danilo will be fulfilling his ambition to play under Pep Guardiola after signing for Manchester City from Real Madrid on Sunday.

[ MORE: Sunday’s transfer rumor roundup | Saturday | Friday ]

The versatile Brazilian defender, who can play on either flank as well as at center back, signed a five-year contract to increase City’s threadbare options at full back.

“There has been strong interest from other clubs, but it has always been my ambition to play for Pep Guardiola,” Danilo said. “As soon as I heard of his interest, I knew immediately I wanted to be a City player.”

City has a shortage of wide defenders after releasing Gael Clichy, Pablo Zabaleta and Bacary Sagna last month and then allowing Aleksandar Kolarov to move to Italian side Roma on Saturday. Kyle Walker, who joined from Tottenham, was the only other full back available to City manager Pep Guardiola before the signing of Danilo.

[ MORE: Mourinho quells speculation of Gareth Bale to Man United ]

“Football is very dynamic and it requires quality players in every position, so I think a player who can play in different positions at a good level has an advantage, and becomes very important for the team as well,” said Danilo, who is awaiting his British work permit. “I prefer just to play. I don’t have a favorite position. I am used to playing as right-back but any time I’m on the pitch in the starting 11, I’m always happy.

“He (Guardiola) told me I’m ready and that I can play in several positions, right back, left back, midfield. I just hope to help him out as he expects.”

Danilo is leaving Madrid two years after joining from Porto, having won back-to-back Champions League titles and the Spanish title once. Financial details of the transfer to City were not disclosed.