Thinking about statistics and football
by Ted Harwood on May 15, 2010 5:41 PM EDT
8 comments
This article on the Arsenal official website earlier this week prompted some thinking in the comments on this blog about the value and usage of statistical data in the world of football. Arsenal are planning on using GPS tracking to build up a database of motion for each individual player on the team in the hopes that analysis of the numbers will help prevent overworking them and thus lessen the frequency of injury. Given Arsenal's focus on staying on the cutting edge of technology, fitness, and nutrition, it is no surprise that the club has taken this step. What remains to be seen, though, is whether this data will actually reduce the number of injuries that players suffer.
This question ties in with the nature of football and with its natural resistance to statistical analysis. There is no sport, and probably no game of any kind, that is as "analog" as football is. (Very) generally speaking, nearly every sport or game is broken up into discrete packets of some kind of information; think of one pitch in baseball, one down in American football, one possession in basketball, one move in chess. Ice hockey approaches football in its flow, but nonetheless has developed a somewhat more robust statistical analysis, perhaps due to the higher incidence of scoring. These sports, with their quantifiable events that accumulate into nice, large, meaningful sample sizes across players, seasons, and teams, lend themselves to math in a way that allows for evaluation and prediction in a way that football seems to defy.
Football statistics are traditionally limited to goals and games played. Recently, with the advent of Opta stats and things such as the Guardian Chalkboards, more numbers are available, such as distance traveled during a match. Systems now track every pass and every tackle during matches, track average pitch position, and every shot vector. This data is invaluable when analyzing a single match, but less valuable when evaluating a single player or predicting how he will play in the future, as the data relates not only to his ability but also to the tactics of the team, the tactics of the other team, and the general flow of the play. Unlike baseball, football is not a matter of a player confronted with the same situation thousands of times in his career with quantifiable variables, but rather a player faced with thousands of similar situations with almost infinitely small variations that make comparison tricky over the long haul.
Thus, the GPS injury system faces a number of challenges. While tracking distance, load, and speed across both matches and training for all players will provide a lot of data, it cannot account for the fact that the injuries that really knocked Arsenal's chances this year had little to do with fatigue or wear, and more to do with Giorgio Chellini and Ryan Shawcross playing recklessly.
The injury to Cesc Fábregas, on the other hand, may have more to do with fatigue, but this raises another question. Cesc only played 36 matches this year, missing time in December both before and after the Villa match, and he missed time in April and May following the first leg of the Barcelona tie. 36 matches does not seem like much, but one must consider that Cesc runs as much as anyone on the team, gives his all every time he plays, and takes on a lot of physical punishment from opponents trying to stop him playing. If GPS data were to show that Cesc needed a rest based on information collected over a number of years, though, would Wenger rest him? Does Wenger not rest him every chance he gets already?
I'm not against Arsenal utilizing the GPS system, for the same reasons that I am not against pitch counts in baseball (although, of course, pitching is a repetitive stress situation, and football is not in the same way). But I do wonder, given opponents' approaches to stopping Arsenal and the sheer number of matches that Arsenal play every year, if this data is the answer, or if it simply another layer on top of the mystery of why Arsenal suffer more injuries than other clubs.
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Data itself is never the answer
I think the use of the GPS tracking information will just be another arrow in the quiver, so to speak, and not the entire basis for a training regimen. Whenever a large amount of data flows into an organization, the key is to have someone in that organization that can analyze the data and use it to come to a conclusion; it’s no good to collect data just for the sake of having it.
Arsenal revolutionized the nutritional basis of training when Arsene took over – no more booze, no more pies, healthy food in the training room at all times – and they’re poised to do the same thing in this arena. I hope they succeed.
To your larger point of stats in soccer, I think you’re right on when you say that the Opta stats are good within a match but not across a match or a season. Strangely enough, I could see defensive stats catching on more than offensive ones. It seems like it’s helpful to know that a right back makes, say, 34 tackles in a game when everyone else on the back line makes 21 because it tells you that the 34 tackle player isn’t afraid to get close to a player with the ball and isn’t afraid to close him down. On the other side of the ball, the fact that a player makes 55 passes a game but only 20 of them are successful is relatively meaningless because what if 50 of those 55, and 15 of the 20 complete, were sidefooted balls to a linemate in the center circle that led to nothing in particular? That doesn’t tell us anything about the quality of the passer.
I think statistics have their place, I just don’t know, to put it in corporate terms, what the use case for them is in soccer yet, if there is one. It will be interesting to see how the GPS thing develops.
I honestly don't see stats that way
For defensive stats, they could be explained in so many ways. For Arsenal this season, it was obvious that the left flank was much weaker than the right flank. So in the period of games that Traore was maning the left flank (supposdly), he may have had more tackles than Sagna did on the right side, but that could easily be attributed to the fact that the oppenent realizes the weakness and specifically targeted Traore all game. This also happened when Clichy came back from injury, they attacked his flank all game long and while he may have made tackles, he struggled mightily for awhile. As well, some defenders prefer to defend off the ball more aggresively and more conservative while the player they are defending and not actually ‘tackle’ as much. This doesn’t even start the conversation of what is considered a tackle, and what isn’t.
As for the passing stat. Denilson supports ALWAYS point to his success rate in passing to justify his worth on the pitch. While he has an extremely high rate of success, his passes are most often horizontal and never advancing the plan, perfering his teammates to iniatate the attack. This would make you see him as a Defensive midfielder, but can you even call him that with his terrible defensive awareness and lack of aggression? Denilson has the highest passing success but I don’t think you can make an arguement for him being a better passer than Fabregas, Diaby, Nasri, Ramsey, and Rosicky, all who completion rate is lower.
The biggest problem with stats in football is that in order to compare stats and to get into advanced stats and compare players is that you need a Constant as the base to start the converstation, and there simply is no constant in which to do this.
I think we're saying the same thing here
The question that your comment raises, that I was trying to raise in mine, is: so what? You said
For Arsenal this season, it was obvious that the left flank was much weaker than the right flank
The stats do indeed bear that out. The question is, how do you go about addressing that weakness? You correctly say “this doesn’t even start the conversation of what is considered a tackle and what isn’t” – and that’s the key. It’s not like Arsenal can look at their team and say “we’re in need of some improvement on the left side” and then comb through the stats and pluck out the left back in the league with the highest tackle rate, because as you say – what is a tackle? What if most of a player’s tackle rate is actually a 50/50 split between tackles and diving?
It’s just incredibly difficult in soccer to figure out what the overarching value of statistics is, as far as roster construction and improvement goes.
Before we get GPS's,
I want FIFA to give those damn refs some video playback technology. Or a 4th linesman.
I'd go with a second referee instead of a fourth linesman
One per half of the pitch. This of course raises all sorts of consistency-of-calls questions but still, it’s worth exploring.
I'd go for video Technology
The fact that FIFA is refusing to use Technology in a multi-million (or is it Billion) industry, which causes clubs, players and their owner millions of dollars every missed call is absolutely absurd. What other industry is so far behind the times like this?
It's billions. Many, many billions.
and the rationale that FIFA (or UEFA in this case) uses to not go the video evidence route is that the event that people seem to most want video evidence for – disputed goal rulings – doesn’t happen often enough to warrant the disruption to the game that video evidence would cause. As much as it pains me to say it, I see their point – disputed goals are jarring, high-profile events but it’s not like it’s a rampant problem in the game that happens 2-3 times every game, so FIFA/UEFA’s seemingly taking an if-it-ain’t-broke-don’t-fix-it approach.
The problem is, that misses the point. There’s more ambiguity in soccer refereeing than there is in almost every other sport, and video evidence, used properly, can help impose a standard across the game as a whole. Referees already use video as training, UEFA has a seminar before every season that uses extensive video in order to illustrate what it wants its referees to do, so why not use it in matches? Or at least do those seminars every week/month during the season so players know what to expect.
I'm for anything that can keep our boys on the pitch
Whether it be GPS, strict diet, workout routines, or voodoo. I don’t care, I just want to win.
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