Wednesday, November 11, 2015

Swan Dive

Back at the end of August, right before an earlier enforced break in the soccer calendar to celebrate nationalist sentiments, Swansea were doing pretty well. Undefeated and on 8 points, the Swans were sitting in the top 4, recording a draw with Chelsea and a defeat of Man United. More than that though, a lot of the advanced statistics were supporting their place in the table, leading to several commentators saying that they were "for real", including this tweet by Michael Caley:
Now, Swansea sit 14th in the table, despite having faced one of the weaker schedules in the Premier League (in terms of opponent points per match). They have a -4 goal difference, and while their shots on target difference is better (+.5 shots per game), their expected goals difference is now negative as well. So what happened?

For me, the answer becomes clear if we look at Swansea's first two matches. In the 52' minute of the Chelsea match, Thibaut Courtois received a red card, reducing Chelsea to ten men. Chelsea had one shot on target the rest of the way, Swansea had five (including Gomis' penalty). Against Newcastle, Daryl Janmaat picked up a red card in the 42nd minute, reducing the Magpies to ten men. Newcastle had no shots on target following the dismissal, Swansea had three including Ayew's insurance goal. In both games, the red card allowed Swansea to dominate proceedings in a way that was not happening when the opposing team had a full complement of players. This is hardly surprising, given that only one team this season has gone on to prevail when one of their players received a red card with more than 15 minutes remaining (Chelsea against West Brom, for those wondering). A man advantage is such a huge bonus that it becomes hard to take statistics from such games seriously (see City v. West Brom last year), and Swansea's early season stats undeniably got a huge boost from those two matches being included, and led to them being overrated early on (their dismantling of relegation-bound Sunderland didn't hurt either).

Should games with red cards be included in a team's statistics? Obviously, that depends on the question you are trying to answer. If you were making the case that Swansea were playing very well in the first four games, I absolutely think those should be included. In both cases, the red cards were probably deserved, and Swansea did go on to perform at a high level in those games. If you are making the case that they were likely to continue to perform well (as the above prognosticators were), I think they probably shouldn't be included (or at least not stats following the red card), particularly in such a small sample. Red cards are relatively rare events, there were only 71 in 380 Premier League matches last term, and there are even fewer that actually had an impact on the game (due to the accumulation of yellows and general ref tendencies, red cards are more likely to be shown late in matches). Even if the red cards were earned by Swansea's play, the stats accumulated from when they were 11 v 10 is probably not reflective of their true talent level. Moreover, as we saw with James McCarthy's tackle on Dmitri Payet this past week, deserved reds are not always given by refs, and there is no way for Swansea to control the referees (short of channeling Alex Ferguson).

There's still a definite shortage of good data out there on football, and oftentimes the tendency is to use whatever we can get. Still, I think this is example shows that it's just as important to know when to exclude data as it is when to use it.

Monday, November 9, 2015

The Second City

Upon winning the FA Cup in 2011, Manchester City fans serenaded Patrick Vieira for his incredible accomplishment: "Patrick Vieira, he's won it five times!" His glittering club and international career as a player is indeed impressive, and he played with a tenacity and grace that is rarely combined in a footballer. Now the former France midfielder has been appointed manager of New York City FC, despite having won zero games as a manager of a professional team. City Football Group, having parted ways with Jason Kreis, felt that the former manager of the Elite Development Squad at Manchester City was the best choice for the role, and most of the fans agree with them:

And yet, I can't help but feel disappointed by the change, as once again City Football Group are putting the needs of Manchester first, and leaving the greatest city in the world in second.

It's easy to see the logic from City Football Group here. Vieira is a high-profile name capable of controlling big stars like Lampard, Villa, and Pirlo. City's hierarchy rate Vieira very highly and clearly see him as a long-term successor to Pellegrini (or Guardiola), and moving him into management at a sister club gives him a chance to take the next step in his development. There's also no question that Kreis underwhelmed as NYCFC manager. Making the playoffs always seemed to be an exceedingly high target, particularly since Lampard and Pirlo didn't join until midway through. However, a porous defense, attack highly dependent on star power to bail out a poor system based on meaningless possession, and misuse (or non-use) of players like Poku and Shay Facey was probably enough to convince CFG that Kreis wasn't the right choice in the long-term. A change needed to be made, and CFG had someone ready and willing to step in who would be able to help the City philosophy take hold in New York. Perfect fit.

However, it's difficult to see such compelling reasons from the NYCFC side of things. There are certainly more experienced options out there for the role. Vieira did have a fantastic playing career, but that by no means guarantees success as a manager (as this recent Gab Marcotti post documents). He managed the EDS side, but that should in theory have a different fundamental goal (player development) than a professional team (winning matches). He has no experience with MLS, either as a manager or a player. The appointment is bound to be short-term, given his and CFG's evident long-term plan to groom him for the Manchester City job. There's no doubt he is an intelligent observer of the game and is a promising coach, but NYCFC are obviously expected to achieve success on a short timetable and an inexperience manager is unlikely to hit the ground running without any hiccups.

This is not to say that Vieira won't succeed at NYCFC. He certainly could, and a full year with Lampard, Pirlo, and Villa could lift NYCFC into the playoffs next year. But it's yet another example, as with the Lampard fiasco and several other incidents, that the decisions being made at NYCFC are made with Manchester City primarily in mind, and this could do long-term damage to the emerging fanbase of NYCFC. New York City FC and Manchester City FC are often described as "sister clubs", but to me it looks more and more like there's a mothership in Manchester, and everything else revolves around it.

Monday, November 2, 2015

City Is Kevin De Bruyne's Team Already

After scoring the winner against Sevilla two weeks ago, Kevin De Bruyne was asked if he could have imagined such a fine start to life at Manchester City. He replied, "Probably not. It feels good. Obviously I know I didn’t play my best game here but I am very happy to give the team the three points and it was very important for us." Lost in the admiration of his winner was the fact that he was absolutely correct in his assessment: for large stretches of the game, he misplaced passes and was caught in possession time and time again. At the same time, he was responsible for the moment of brilliance that won the game, and it's fair to say we probably wouldn't have won without him. This game was a perfect illustration on how dependent City have become on De Bruyne, and why he'll need to keep improving in order to keep City at the top in the Premier League and Europe.

In order to demonstrate De Bruyne's influence on City's attack, I'd like to use a stat called Usage Rate. Borrowed from basketball analysis, it looks at how many possessions a team has (measured by counting total shots, unsuccessful passes, and unsuccessful take-ons) and what percentage of them a given player is responsible for the last action of the possession (has a shot, key pass, unsuccessful pass, or unsuccessful take-on), weighted by minutes played*. It's obviously imperfect, but Usage Rate helps to get a basic statistical understanding of how heavily involved each player is in a team's attack. I have listed City's statistics for the first eleven games of the Premier League season below (players with 180+ minutes only):

Minutes Possessions Used Usage Rate Positive Outcomes Negative Outcomes Ratio
De Bruyne
559 125 19.18% 34 91 27.18%
795 131 14.11% 47 84 35.92%
893 133 12.77% 32 101 24.06%
417 62 12.76% 19 43 30.60%
482 71 12.63% 32 39 45.07%
682 98 12.31% 34 64 34.71%
765 100 11.21% 34 66 33.99%
545 65 10.21% 38 27 58.54%
540 61 9.68% 9 52 14.75%
244 27 9.48% 12 15 44.44%
900 90 8.57% 11 79 12.22%
968 96 8.51% 18 78 18.74%
630 58 7.89% 7 51 12.07%
333 28 7.21% 5 23 17.86%
185 14 6.49% 3 11 21.43%
675 44 5.59% 2 42 4.55%
900 49 4.67% 1 48 2.04%

As you can see, there are some clear trends here. It's not surprising that Hart, three central defenders, and Fernando are the lowest in Usage Rate, as they play positions focused on defending, not attacking. Silva and Toure being near the top also makes sense, as they have been the fulcrums of our attack for the past 5 years. Kolarov's presence shows how much we rely on his width on the left to create problems and his role in set pieces. However, De Bruyne being well above everyone is a surprise, given how new he is to our team and system. He has been critical in filling the void left by Silva as the main playmaker in the side, using up a lot of the possessions the Spaniard would have taken.

The problem is that while he has certainly been very involved in the attack, it hasn't always brought the best results. Of the 125 possessions De Bruyne has used, only 34 had a positive outcome (a shot or key pass) and 91 had a negative outcome (an unsuccessful pass or take-on). That means just 27% of his possessions have positive outcomes, which is the lowest of any attacking mid or forward on the team. To a certain extent, it makes sense that a player's efficiency will drop the more of the ball he sees. Defenses will focus more on him, closing down earlier and not giving him the space to pass or shoot. At the same time, it speaks to the fact that De Bruyne is not the finished article. In the game against Sevilla in particular, he had a lot of unforced passing errors, often trying to get that killer final ball. That's not always a bad thing, given City last year were probably too careful in possession, and could have used someone like De Bruyne who is constantly trying things. However, the number of times he gives the ball away stifles the attack and puts pressure on the defense, especially since we commit our fullbacks (especially Kolarov) to the attack frequently.

I truly believe De Bruyne has the tools to be the best attacking player in the Premier League, as his touch, finishing ability, and eye for a pass are evident for all to see. However, it's only when he's able to marry efficiency and volume that he will be able to take the next step, and help City take the next step as a team.

Note: All data from

*Usually, Usage Rate also weights for league pace (measured by average possessions per game), but given there are no league-wide comparisons (and perhaps more importantly I haven't done the league-wide stats yet), I'm not including for this article.