Monday, September 29, 2014

Who is the Most Important Passer for Every EPL Team?



The above chart shows the most important passer for every team in the EPL, based on pass usage rate.  Pass usage rate is calculated by taking a player’s passes per 90 min and dividing it by their team’s passes per 90 min.  It represents the share of their passing contribution to their team.


Typically, a team’s most important passer is either a central midfielder or a defensive midfielder (see: Yaya Touré, Morgan Schneiderlin, Gareth Barry).  Players in those positions should be the primary conduits for ball circulation.  Therefore it is troubling—though not surprising given their form—that  both Liverpool and Manchester United’s most important passers so far are defenders (Dejan Lovren and Tyler Blackett?!).  This is an indication that both teams, while strong in possession, have not done a good enough job of advancing that possession to more dangerous areas of the field.  It is still very early in the season, though, and the expectation is that Liverpool should be fine and Manchester United’s recent acquisitions Ander Herrera and Daley Blind will help.  Also of note, West Ham’s Mark Noble—who has been getting recent support for an England call-up—is leading the EPL in pass usage for the second consecutive year.

Tuesday, September 16, 2014

Usage Rates: A Primer

This article originally appeared in Stats Bomb




If there was one over-arching principle for analyzing soccer statistics, it might be “context is king.”  For example, Arsenal’s Bacary Sagna averaged 54.5 passes per 90 last year and West Ham’s Mark Noble averaged 53.2 passes per 90.  Intuitively, our first reaction is probably that both players exhibit roughly the same level of passing influence—with maybe the slightest of edges given to Sagna. But we are not controlling for the fact that Arsenal led the EPL with 569 passes per game while West Ham was second from bottom, averaging 326 passes per game.  To adjust for this disparity we take each player’s passes per 90 and divide it by their team’s passes per 90, thereby creating a pass usage rate for each player.

Passes / 90
Team Passes / 90
Pass Usage Rate
EPL Rank
Mark Noble
53.2
326.2
16.3%
1
Bacary Sagna
54.5
569.4
9.6%
142


Once adjusted, we now see that Noble was a significantly more influential passer for his team than Sagna and actually recorded the highest pass usage rate of any player in the EPL.  It should be noted that usage rates are not a predictive metric, nor are they meant to be, but they are a very useful tool to help us understand a player’s influence on their team and separate “team effects” from individual statistics.

General Usage Rates

Pass usage rate is—to this point—the most widespread usage rate.  Devin Pleuler recently published a nice write-up on the subject, which also introduced the idea of network centrality.  Pass usage rate is a “general” usage rate in that it does a good job of approximating a player’s general influence to their team.  Another general usage rate is the touch usage rate.  It differs from pass usage rate in that it measures more actions than just passes attempted (i.e. if a player receives a pass and shoots or turns it over before attempting another pass), so it is potentially a better proxy for general player activity.  We have also included Arsenal player’s pass and touch usage rates to further exemplify these differences.




 (Arsenal, 2013-2014)

Touches / 90
Pass / 90
Touch Usage Rate
Pass Usage Rate
Abs. Difference
Mikel Arteta
95.7
80.5
12.2%
14.1%
1.9%
Aaron Ramsey
98.5
77.3
12.5%
13.6%
1.0%
Mesut Özil
86.3
68.6
11.0%
12.1%
1.1%
Santiago Cazorla
89.8
67.1
11.4%
11.8%
0.4%
Tomas Rosicky
76.7
64.1
9.8%
11.3%
1.5%
Jack Wilshere
82.7
63.8
10.5%
11.2%
0.7%
Mathieu Flamini
77.4
63.1
9.9%
11.1%
1.2%
Nacho Monreal
82.0
55.0
10.4%
9.7%
0.8%
Bacary Sagna
82.1
54.5
10.5%
9.6%
0.9%
Per Mertesacker
61.8
48.8
7.9%
8.6%
0.7%
Kieran Gibbs
76.0
47.7
9.7%
8.4%
1.3%
Lukas Podolski
62.4
46.1
7.9%
8.1%
0.1%
Laurent Koscielny
57.9
41.7
7.4%
7.3%
0.1%
Olivier Giroud
50.4
32.5
6.4%
5.7%
0.7%
Wojciech Szczesny
39.7
18.0
5.1%
3.2%
1.9%





Attacking Usage Rates

You can measure a player’s attacking influence by looking at their shot usage, key pass usage, and general shot contribution usage.  These were the top 10 in the EPL last year.


Shots/90
Shot Usage (%)
KP/90
KP Usage (%)
Shot Contr./90
Shot Contribution Usage
Luis Suárez
5.5
32.1%
2.6
20.4%
8.14
47.5%
Christian Benteke
2.8
25.0%
2.0
22.7%
4.82
42.5%
Marko Arnautovic
2.9
25.5%
1.9
22.2%
4.79
42.5%
Wayne Rooney
3.7
26.8%
2.1
18.6%
5.77
41.7%
Jason Puncheon
2.8
25.3%
1.8
21.3%
4.51
41.3%
Robert Snodgrass
2.5
20.2%
2.3
25.9%
4.83
39.3%
Wilfried Bony
3.9
30.1%
0.9
9.0%
4.84
37.1%
Kevin Mirallas
3.1
21.2%
2.4
18.2%
5.48
37.1%
Philippe Coutinho
3.6
21.2%
2.5
24.3%
6.13
35.8%
Rickie Lambert
3.3
23.4%
1.7
16.3%
5.02
35.7%




Defensive Usage Rates

Defensive statistics remain a relatively under-researched domain in soccer analytics.  When people do talk defensive statistics, usually only tackles and interceptions are discussed.  This is a mistake, as tackles and interceptions combine to only comprise 24.4% of turnovers.  Any overall defensive usage rate should also include clearances and recoveries. 

2013-2014 EPL Turnovers (By Type)
Tackle
            11,153
12.6%
Interception
            10,435
11.8%
Clearance
            23,459
26.6%
Recovery
            43,236
49.0%

            88,283
100.0%


Here are the top 10 in overall defensive usage rate in the EPL last year. 


Turnovers Forced / 90
Defensive Usage Rate
Nemanja Vidic
20.0
15.9%
Phil Jagielka
17.8
15.9%
Marcos Alonso
16.0
15.4%
James Collins
17.3
15.3%
Nemanja Matic
17.2
15.1%
Martin Skrtel
18.7
15.0%
Martín Demichelis
16.3
14.7%
Laurent Koscielny
17.7
14.7%
Curtis Davies
16.9
14.7%
Youssuf Mulumbu
17.5
14.5%


It would also be informative to look at tackle, interception, clearance and recovery usage rates, respectively to get a sense as to a defender’s tactical responsibilities.  For example, Nemanja Vidic does most of his work with clearances (11.4 of the 20.0 turnovers he forces) and is responsible for nearly 31% of all of Manchester United’s clearances when he is on the field.

Thursday, August 28, 2014

The Rise of the "Technical Era"

This article originally appeared in Bloomberg Sports


If you watched Manchester City’s 3-1 victory over Liverpool earlier this week you would have been treated to a high level of football.  Both teams pinged the ball around in a desperate search for space, looking to score whilst simultaneously being wary of the opposing team’s counter-attack.  Possession was not conceded lightly.  Each team had approximately 100 turnovers and the average pass sequence per possession was approximately 5.7.  In short, the match was a far cry from the stereotypical long ball style traditionally associated with English football (note: only 8 of the 27 players featured in the match were English).  While just one match, this supremely technical style of play is indicative of a larger trend in the EPL.  Passes per game are up 20% since the 2009-2010 season, and a full 97% of that trend is attributable to the rise in the number of short passes.  Correspondingly, there has also been a drop in the number of turnovers committed.





These are very significant stylistic changes we are seeing in a relatively short period of time.  Out of curiosity, we looked at the other major leagues of Europe to see if this trend is particular to the EPL.  What we found is that the same exact trend is taking place all across Europe (and perhaps elsewhere).  In addition to the EPL, we looked at the Bundesliga, La Liga, Ligue 1, and Serie A (“The Big 5”).  Based on evidence of the first couple match days of this season in Europe, the rise of the “Technical Era” still seems to be in the ascent.  It will be worth watching where it leads us.




Monday, August 11, 2014

Ignore Geoff Cameron at CB at Your Peril



The consensus among most long-time observers of Geoff Cameron is that the American international is best-utilized as a central defender or, potentially, as a central defensive midfielder.  Not surprisingly, Cameron seems to agree with this assessment.  Most do not see Cameron as a natural right back.  And yet, that is where he has carved out a role for himself at Stoke.  Cameron made 36 of his 37 appearances in that role during the most recent EPL campaign.  While he performed ably, neither did he excel as he was unable to make full use of his athleticism— arguably Cameron’s best attribute.  But, there is growing speculation that other European teams see in Cameron what he sees in himself: an international-caliber center back.  The evidence, though not conclusive, indicates that Cameron should have no trouble finding a role in central defense for another team.

While we have a pretty good understanding of key performance indicators for attacking soccer players, there has been woefully little progress in measuring defensive players and, in particular, central defensive players.  This is understandable: the best attribute for a defender is the attacking play that did not happen – how do you measure that?  This major caveat aside, there is one measurable trait that most of the best central defenders possess— the ability to win aerials.  Opta measures both the # of aerials contested in a match and the % of these aerial battles “won” for every player.  Although he played as a right back, Cameron demonstrated an aerial prowess that compares well to his central defensive peers.


Skeptical that aerial win (%) means anything?  Here are the players with 70%+ aerial win.

We do have some more recent data on Cameron as a central defensive player.  We looked at his games vs. Turkey, Nigeria, Ghana, Portugal, and Belgium (he played as a central defensive midfielder this game).  We evaluated Cameron on three key central defensive indicators: aerial win (%), # of clearances, blocked shots (as a percent of shots conceded).  While not all-encompassing in their scope, these are some of the better indicators we have for center backs.  Here is how this admittedly small sample size of Cameron’s international work stacks up against the best center backs in the EPL (per composite rankings of Whoscored, Squawka, Castrol).  This analysis is in no way definitive, and you are no doubt thinking of that error vs. Portugal, but there is undoubtedly some compelling evidence on Geoff Cameron’s side.