Tuesday, February 18, 2014

Shots Overall vs Shots on Target

Shots Overall vs Shots on Target
By Aaron Nielsen

In my last post I mention my dislike for the stat shots off target especially as a positive stat since it leads to the end of the offensive possession.  Although not keeping up with all the advance analytics in soccer I was unaware of the core of a new statistical evolution or fully aware of the stat TSR - http://grantland.com/the-triangle/what-is-total-shots-ratio-and-how-can-it-improve-your-understanding-of-soccer/

Last night I had a drink with a young and enthusiastic soccer and analytics fan who told me he had some modeling for predicting the most undervalued players in the MLS and wanted me to see his work.  Common in statistics he didn't want to show me much of his work and he basically had a list of players with rankings out of 10 including decimals. Aware of the players through seeing them play and my own work I inquired more how he came up with these evaluation. Basically he said he was a fan of the site whoscored.com but he disagreed with their rating system but used the stat "shots per 90" and "key passes per 90" without any raw data so it didn't surprise me a couple of the players on his list were players who only played a few minutes last season.

I don't use any OPTA work in my material which is the source of all whoscored statistics although since its available and OPTA is regarded as the official stat source. people have been drawn to the data and are using it in their own analysis. Although in comparing the data with my own it seems that "shots per 90" are shots on target + shots off target over 90 minutes of play well "key passes per 90" are the assist that lead to the shot (on & off) target over 90 minutes of play.

I don't calculate key passes in any of my work although I know in conservation with people in Spain that stat has been around for a number of years although there. they counted that as an assist and didn't count what we would normally regard as an assist. Personally its hard for me to get my head around awarding an assist on a failed offensive possession since it's not done in any North American sport but I can see some value if you were very specific on which play it should be counted.

Although awarding it on all shots off or on target makes no sense to me because your giving a player credit when more than half of these opportunities lead to a player missing the net and the opposing goalkeeper getting control of the ball. To further emphasize my point on how a miscue stat shots are to goals I went through the top leagues in the world and looked at the current top 20 in goals not including penalties, shots in total, and shots on target all based on the current data although the MLS is the complete 2013 regular season.

English Premier League
Players Club Goals Rank Shots (on & off) Rank Shots (on) Rank
Suarez Lvp 23 1st 118 1st 56 1st
Sturridge Lvp 16 2nd 62 11th 32 3rd
Aguero Mnc 15 3rd 70 4th 35 2nd
Remy New 11 4th 69 5th 26 7th
Hazard Chl 10 5th 53 19th 28 4th
Rodriguez Sth 10 5th 69 5th 25 9th
Coutinho Lvp 3 NA 71 3rd 23 13th
Barkley Eve 3 NA 62 11th 13 NA
Paulinho Tot 4 NA 55 17th 16 NA
German Bundesliga
Players Club Goals Rank Shots (on & off) Rank Shots (on) Rank
Aubameyang Dor 13 1st 49 14th 30 6th
Mandzukic Bay 12 2nd 46 18th 31 4th
Ramos HB 12 2nd 62 3rd 33 2nd
Losogga Hsv 10 4th 53 7th 31 4th
Lewandowski Dor 10 4th 78 1st 46 1st
Reus Dor 5 NA 71 2nd 33 2nd
Kruse Bay 5 NA 53 7th 26 8th
Hunt WB 1 NA 46 18th 19 NA
Italian Serie A
Players Club Goals Rank Shots (on & off) Rank Shots (on) Rank
Immobile Tor 13 1st 54 16th 29 7th
Tevez Juv 12 2nd 86 2nd 41 2nd
Palacio Int 11 3rd 58 13th 28 10th
Toni Ver 11 3rd 72 6th 31 5th
Llorente Juv 10 5th 39 NA 23 17th
Balotelli ACM 8 15th 101 1st 42 1st
Diamanti Bol 2 NA 82 3rd 27 12th
Candreva Laz 3 NA 74 5th 23 17th
Spanish La Liga
Players Club Goals Rank Shots (on & off) Rank Shots (on) Rank
Ronaldo RM 17 1st 160 1st 72 1st
Costa AM 17 1st 76 3rd 43 2nd
Sanchez Bar 15 3rd 46 16th 25 9th
Griezmann Soc 14 4th 69 4th 38 4th
Benzema RM 14 4th 58 6th 26 9th
Messi Bar 11 6th 83 2nd 40 3rd
Rakitic Sev 7 20th 62 5th 21 19th
Di Maria RM 3 NA 48 14th 27 7th
Dutch Eredivisie
Players Club Goals Rank Shots (on & off) Rank Shots (on) Rank
Pelle Fey 18 1st 84 2nd 50 1st
Castaignos Twe 13 2nd 66 4th 39 3rd
Finnbogason Hen 13 2nd 71 3rd 37 4th
Promes Twe 10 4th 49 10th 31 6th
Johannsson AZ 10 4th 37 NA 24 18th
Depay PSV 6 NA 95 1st 42 2nd
Tadic Twe 4 NA 61 6th 29 8th
Chery Grn 4 NA 49 10th 25 12th
Major League Soccer
Players Club Goals Rank Shots (on & off) Rank Shots (on) Rank
Di Vaio MTL 20 1st 118 2nd 53 2nd
Magee Chi 17 2nd 114 3rd 50 3rd
Camilo Van 17 2nd 123 1st 55 1st
Oduro Clm 13 4th 92 8th 36 5th
Fagundez NE 13 4th 55 NA 29 10th
Bruin Hou 8 NA 98 5th 30 7th
Higuain Clm 5 NA 86 10th 31 6th
Zardes LA 5 NA 78 12th 23 6th

From my view there is no case where shots in general equals goals better than shots on target does as well based on the examples there is many cases where players have a large amount of shots but scored very small amount of goals. And in almost every case a player in the top 20 of scoring ranked higher or equal in shots on target than he did on total shots.

This is true in team data as well as Juventus was the top shooter in the Champions League with 101 shots but only scored 9 goals, Tottenham and Newcastle have 40 more shots than Arsenal in EPL this season. Braunschweig has more shots than Schalke in the Bundesliga yet scored 26 less goals and in La Liga last place Real Betis has more shots than league leaders Atletico Madrid.

This is a trend I been seeing since I started tabulating data for soccer including the most extreme story in Japan J-League in 2001 when Brazilian Wanger Lopes played for relegated side Avispa Fukuoka and had 186 shots in only 34 game season although only 41 were on target and seeing other players with shots in the 30 but only one or two on target I decided to stop recording shots and concentrate only shots on target and in my analysis going over a number of seasons I'm confident with that choice.

In truth some of this new analytics have been around in football for many years with people involved with clubs telling me they were looking at play per 90. shooting analysis, and even expected goals since the early 2000's although I'm encouraged by the enthusiasm by people especially younger ones to look at statistics and analytics. This being said I think there is a fear of group mentality where everyone jumps on idea and that stat becomes a new trend and even in North American sports there have been ratings and other forms of data analysis that were loved at one point but lost its value when it really made no difference on the field. So I love the sharing of ideas but I feel proof of concept is where the value is.

My acquaintance and I at the end of the night agreed to disagree his view was their was a lot more work online proving his concept over my concerns and was dishearten by my initial response as he thought I could introduce the work to MLS clubs in which I told him his best option was to approach OPTA since he was using their work to produce his analysis.  

Although when I got home I felt it unfair just to dismiss a concept especially one that is popular so hopefully this sample of data shows my point and I can include many more samples if wished. Although my footballing view on the matter is - Do I want a player who is willing take a shot? The answer is no, what I want is a player who can score and taking shots in my view doesn't mean your going to score especially if a large percentage are off target or easy saves for the keeper.

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