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.

Report: Kyle Walker a top target for Manchester City

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Manchester City could be looking to bolster its backline further this summer, and the Citizens could turn to Tottenham for help.

[ MORE: Man City closing in on acquiring Monaco’s Silva ]

According to ESPN FC, Pep Guardiola‘s side is growing more and more enamored with Spurs defender Kyle Walker and believes City can acquire the experienced outside back prior to the 2017/18 Premier League season.

With City already losing Pablo Zabaleta and Bacary Sagna since the end of the PL season, Guardiola will have to address the club’s lack of depth at outside back.

Several other big clubs have been considered in the running for Walker’s services, including Chelsea, Manchester United and Bayern Munich.

The 26-year-old has been at White Hart Lane since joining Spurs in 2009 from Sheffield United and has made 222 appearances for the club in that span.

Alaves eyes upset of Barcelona in Copa del Rey final

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BARCELONA, Spain (AP) The final of the Copa del Rey pits Barcelona’s star power against a tiny Basque Country club whose biggest weapons are its grit and gnawing hunger for a taste of glory.

[ MORE: Man City closing in on Monaco’s Silva ]

Win or lose, Alaves is savoring the cup final on Saturday as the perfect finish to its first season back in Spain’s topflight in an decade.

[ MORE: Three key battles ahead of Chelsea-Arsenal FA Cup final ]

But to have a chance of winning the first major trophy in its 96-year history, Alaves’ ragtag collection of journeymen has to be squeezed of every ounce of effort by coach Mauricio Pellegrino to upset the cup-holders led by Lionel Messi.

One statistic illustrates how daunting their task will be: Messi, all by himself, has scored exactly as many goals as the entire Alaves squad this season, with 53 across all competitions.

“We will need to play a very complete match to have a chance, but we are a team that always competes to the maximum,” said Pellegrino, who is completing a noteworthy first season with the club.

The final will be the last competitive match at Atletico Madrid’s Vicente Calderon Stadium. An exhibition match the next day will be its farewell before demolition.

The final will also be the last match for departing Barcelona coach Luis Enrique, who could bow out with a third straight Copa del Rey.

Here are some reasons Alaves can believe in an upset for the ages:

DONE IT BEFORE

Alaves has already toppled Barcelona this season.

A shocking 2-1 victory at Camp Nou on Sept. 10 was Alaves’ first win since its return to the first division following 10 years in the second and third tiers.

That surprise victory set it on its way to overachieving all campaign. It reached the Copa del Rey final by defeating the more talented Celta Vigo in the semifinals, and finished the league in a meritorious ninth place.

The bad news is that Barcelona showed no mercy back in Vitoria, where Luis Suarez scored twice in a 6-0 rout.

NO SUAREZ

But Suarez won’t be available for Barcelona on Saturday, when he serves a one-game suspension after being sent off during the semifinals against Atletico Madrid.

Luis Enrique could start Paco Alcacer in his place up front alongside Messi and Neymar.

OLD AND YOUNG

Alaves is not devoid of talent.

The 19-year-old right back Theo Hernandez, who is playing on loan from Atletico, is drawing rave reviews and interest from European powerhouses, including Real Madrid.

Marcos Llorente, a 22-year-old Madrid reserve player also on loan, has impressed as a defensive midfielder.

Captain Manu Garcia, at 31, is the only player who has been with the team through its rise from the third tier in 2013.

“Our coaches are telling us that by working as a team just like we have all year, we have a chance to win,” Garcia said.

OH SO CLOSE

Alaves came ever so close to winning the 2001 UEFA Cup when it defied expectations in its first European campaign by reaching the final against Liverpool.

Jordi Cruyff, son of Dutch great Johann Cruyff, scored late to level the thriller at 4-4 and force extra time, only for Alaves to succumb on an own goal by Delfi Geli.

“I want our fans to enjoy the day,” Garcia said. “I remember (the final in) Dortmund from when I was young. I have many memories of that day and that’s why I ask our fans to be proud of Alaves, and that they make the Calderon into our stadium because that is what we will need it to be.”

MLS at Week 13: Rivalries all around, TFC goes for eight games unbeaten

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Week 13 is here and we’ve got ourselves some pretty tasty matchups, after the weekend got off to a fast start on Thursday night when the Chicago Fire downed FC Dallas.

[ MORE: MLS Power Rankings — Week 13 ]

Meanwhile, the match of the weekend likely comes in the form of Toronto FC taking on the Columbus Crew, as Greg Vanney’s side puts their seven-match unbeaten run on the line at BMO Field.

Several other intriguing fixtures, including multiple rivalries, will take place as well, particularly in the Pacific Northwest as the Seattle Sounders and Portland Timbers do battle.

Toronto FC vs. Columbus Crew — 7 p.m. EDT on Friday

It’s been seven straight matches for the Eastern Conference leaders since they last lost and Toronto FC has become the clear favorite to hoist MLS Cup through the opening two months-plus. Of course that can change in the blink of an eye. We’ve seen that with the Crew as of late, who started out hot before losing four out of their last six and falling to fifth in the East.

Seattle Sounders vs. Portland Timbers — 2:30 p.m. EDT on Saturday

There’s nothing like a Cascadia Cup match. Although both clubs aren’t exactly up to par at the moment, it’s still a rivalry match. That has to mean something, right?

Vancouver Whitecaps vs. D.C. United — 7 p.m. EDT on Saturday

The Whitecaps have picked up some steam lately, winning three of their last four, and unfortunately for D.C. they haven’t had any similar fortunes. Ben Olsen’s group are at the bottom of the East, and had it not been for the Rapids there would probably be more attention on how poorly they are playing.

New York Red Bulls vs. New England Revolution — 7 p.m. EDT on Saturday

Jesse Marsch’s club picked up an important tie against a red-hot Toronto last time out, but now they’ll meet a familiar rival on Saturday as they try to get back to winning ways. Meanwhile, the Revs have played significantly better as of late, scoring six goals in their two most recent outings.

Colorado Rapids vs. Sporting KC — 8 p.m. EDT on Saturday

Simply put, they only good thing the Rapids have on their side is that the match is at home, where the team has captured both of their wins this season. Sporting KC, meanwhile, continues to tear it up at the top of the West.

Minnesota United vs Orlando City — 8 p.m. EDT on Saturday

Orlando has come back down to earth recently, so it’s time for Jason Kreis and co. to reset. Adrian Heath and the Loons continue to suffer through the growing pains of being a new side, something Kreis can relate to from his time in New York, but Minnesota has shown positive signs during the young season.

Real Salt Lake vs. Philadelphia Union — 8 p.m. EDT on Saturday

The Union are looking really good as of late, and the winners of four straight could very well keep it up on the road against RSL, who have struggled to pick up results for much of the season.

San Jose Earthquakes vs. LA Galaxy — 10 p.m. EDT on Saturday

The Cali Clasico takes shape at Avaya Stadium as both west coast sides look for bragging rights out west.

Atlanta United vs. New York City FC — 5 p.m. EDT on Sunday

It was Patrick Vieira’s side that got the best of Atlanta when the two clubs met a few weeks back, and it’s bad news for Tata Martino’s men as NYCFC has caught more steam as they continue to rack up positive results in the Eastern Conference.

FC Dallas vs. Houston Dynamo — 8 p.m. EDT on Sunday

We’ve got ourselves a Texas Derby down in Dallas, and this could be quite the interesting matchup as both sides enter Sunday on a bit of a downturn. It’s evident both clubs have exciting offensive firepower but which side will come out on top?

Emre Can’s insane bicycle kick wins 16/17 PL Goal of the Season

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It was about as good a finish as you’ll see in any season, and Emre Can was properly rewarded by the Premier League for his efforts.

[ MORE: Man City closing in on acquiring Monaco’s Silva ]

The Liverpool midfielder won PL Goal of the Season on Friday for his audacious and seemingly impossible bicycle kick against Watford.

The goal came off a routine cross from Lucas Leiva into the Hornets penalty area, but what Can did next was simply astonishing as contorted his body and acrobatically finished an overhead kick that was the talk of the PL for the rest of the season.

Can, 23, finished the 2016/17 PL season with five goals in 31 matches for Jurgen Klopp‘s side but none can compare to what he achieved at Vicarage Road.