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.

Dempsey still happy to accept USMNT role (which is good)

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Clint Dempsey is tied with Landon Donovan for the most goals in USMNT history, and seems set to continue with the side in some capacity as he threatens to stand alone in American history.

[ MLS: Steve Bruce to Miami? ]

The 34-year-old striker spoke with Steve Zakuani on the Sounders’ web site (video below) and said he’s happy to accept continued call-ups should they arrive from USSF headquarters.

From SoundersFC.com:

“We’ll see what happens,” Dempsey said.” I mean, in terms of what I’ve been able to accomplish with the national team, I’m at peace with it. It’s not really about me. It’s about a group of guys that want to be moving forward.

“If there’s an opportunity that comes where you get to play a role and try to help and I’m feeling good and I’m playing well, then yeah, you’ll never say no. But you know, if the call never comes I’m still happy, still at peace, and focused on being here and trying to make the most of the time I have left.”

There are a number of players whose national team futures should be in question, but Dempsey is in a different class. No one has debated his motor or fuel, and his engine is still there (to complete the Springsteen-esque car comparisons, he remains one of the only things that qualifiers as chrome-wheeled, fuel-injected, and steppin’ out over the line).

If anything, he plays too close to the edge. That’s not something I see as one of the Yanks’ problems right now, so perhaps Dempsey needs to be viewed like Cuauhtemoc Blanco or Carlos Ruiz as a CONCACAF guy who’s around as long as he wants to be a part of it.

I mean, shoot, if Dempsey wants to keep passing the fire to Christian Pulisic and now Weston McKennie, there are far worse ambassadors for the program. He’s the most accomplished field player in recent history, and will be able to share so much when it comes to balancing club and country.

Heck, maybe he needs to be the late era Ryan Giggs of the 2018-2022 USMNT.

Beckham reportedly wants Steve Bruce in Miami

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He’s got the same initials as South Beach, you know?

Steve Bruce is being tipped to be the first manager of David Beckham’s Miami MLS outfit, according to The Sun.

[ MORE: Saturday’s PL roundup ]

It’s going to be some time before Bruce would have the opportunity. The 56-year-old former Manchester United star has Aston Villa in a Football League Championship promotion push, and Miami does not even have a start date for life on an MLS pitch.

Of course, managerial life tends to be short, so there’s no guarantee Bruce will have a job at any point during the build-up to Miami in MLS. And several expansion clubs have named their coach very early in the team building process (Jason Kreis and Bob Bradley amongst others).

Bruce on MLS’ parity-driven playing field, if not as one of the big spenders, would be intriguing to watch. He’s a terrific man motivator and has the connections to combine with Beckham to make something special happen in terms of personnel.

PL Sunday preview: Wayward Watford welcome woeful West Ham

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In a reversal of roles, based on preseason projections at least, Watford welcome West Ham United to Vicarage Road on Sunday (Watch live, 11 a.m. ET, on NBCSN and NBCSports.com) for a clash of mid-table climbers and relegation fighters, respectively.

[ MORE: Saturday’s PL roundup — Man Utd, Chelsea win big… so do Man City ]

Watford began the 2017-18 Premier League season in fine form, winning four of their first eight games and losing just one (to runaway leaders Manchester City, no less). In their last three games, however, the Hornets have conceded eight goals, while scoring just four themselves, and winning zero points. Coincidentally — nor not, perhaps — that three-game slide began at the same time Watford manager Marco Silva‘s name was linked with the vacant manager’s job at Everton. With Ronald Koeman fired almost four weeks ago now, Watford have rejected approach after approach from Everton owner Farhad Moshiri. Silva, for his first three months of efforts, has been roundly praised by the club’s supporters and players alike.

“Everybody could see he changed a lot of things in the team. We had quite a lot of the same players but we improved a lot,” defender Christian Kabasele said this week. “When you have somebody like this and other teams are looking for him it’s important that Watford try to do everything possible to keep him.”

West Ham, meanwhile, started the season poorly and have remained equally so in recent weeks. Slaven Bilic was subsequently fired two weeks and succeeded by David Moyes, who had been out of a job since guiding Sunderland to relegation at the end of last season. Sunday’s bout with Watford will see Moyes make his debut for West Ham, the fourth club to employ him since leaving Everton four and a half years ago. To make matters more difficult, the Hammers’ leading scorer, Javier Hernandez (4 goals), won’t be available after picking up an injury on international duty.

“It’s a clean slate for the entire squad,” Moyes said last week. “They’ve all worked very hard this week and responded in a positive manner to everything we’ve asked of them. It will obviously take time for the players to fully understand our style and methods but the initial signs are very encouraging — they’ve bought in what we are trying to do and that’s a good base for us to build on.”

INJURIES: Watford — OUT: Troy Deeney (suspension), Nathaniel Chalobah (knee), Isaac Success (knee); QUESTIONABLE: Younes Kaboul (hamstring), Sebastian Prodl (hamstring), Roberto Pereyra (hamstring) | West Ham — OUT: Javier Hernandez (hamstring), James Collins (ankle), Sam Byram (thigh), Jose Fonte (foot); QUESTIONABLE: Michail Antonio (ribs)

The 2 Robbies: North London Painted Red

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In today’s pod, the Robbies heap praise on Arsenal’s impressive performance in the North London Derby (00:30), analyze Manchester United’s 4-1 win against Newcastle on the back of Paul Pogba’s return (10:00), ask if this Man City side is the best Premier League side ever (18:25), debate where Kevin De Bruyne’s current form ranks in the league’s greatest ever players (23:45) and pick the best summer signing so far this season (27:15; hint, hint – he might be leading the league in scoring).

Join Earle & Mustoe on The 2 Robbies Football Show, Saturdays at 5pm ET. Listen on the NBCSports Radio App and call 855-323-4622 in the U.S. for lively passionate debate.

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