Sunday, June 19, 2011

Why Wigan Were the Most Unusual Team of the Season: Goal Creation in the Premier League in 2010/11

Roberto Martinez has been in the news quite a bit lately, and for all the right reasons, it seems. His Latics managed to avoid relegation, and he was courted heavily by Aston Villa. He said no, apparently out of loyalty:
"Over the last two years the chairman has been very supportive to me and loyal, and now I feel I need to be loyal and supportive back to him. I haven't finished my job at Wigan Athletic; there is much work still to be done."
So what kind of work has Martinez been doing? Avoiding relegation is undoubtedly a major feat. As The Swiss Ramble, a blog on football finances, pointed out in an analysis of Wigan's financial situation:
"Given their substantial financial disadvantages, Wigan’s ability to survive in the Premier League is a minor modern miracle. They have the lowest revenue in the top tier, just about the smallest crowds, the highest reliance on television money, one of the highest wages to turnover ratios and no cash. As a recent set of accounts drily stated, 'The challenges on the pitch are very much reflected by the challenges off it.'"
Martinez seems to have been doing more than getting lucky, however. But what, exactly? One way to analyze Wigan's survival is to take a look at where their goals came from last season. To put things in perspective, a few days ago, I wrote about goal creation in the Premier League during the 2010/11 season. The upshot: for the league as a whole, most goals came from open play (about 70% or .93 goals per team and match), and the smallest number and proportion (2.6% or .036 per team/match) came from free kicks.

These overall totals are interesting because they give us a sense of where goals in top level professional football come from. Of course, this doesn't mean that all teams play the same style of football or create chances and goals in the same way, and it doesn't tell us whether Wigan (or anyone else for that matter) stood out. So how much variation in goal creation was there across individual teams last season? Can we recognize differences in team strategies by the way they managed to put the ball in the back of the net?

To answer the question, I went back to the data on shot and goal creation collected from the Opta/Guardian Chalkboards and calculated numbers and percentages of goals created from different match situations for each team. And lo and behold, they show that teams like Arsenal and Wigan created goals in very different ways. To see how much they differed and in what way, the next graph plots goal creation (the number of goals per match) from different match situations for each of the teams over the entire 2010/11 season.

You may be surprised to find out that the patterns of goal creation for each individual team follow the overall pattern of the league only in one important respect: all teams score more goals from open play than anything else. But once we go beyond this basic pattern, we see lots of differences in how teams created goals in 2010/11.

Compare Wigan and Newcastle, for example (leaving aside goals from open play for the moment): while the Latics created most of their goals from fast breaks, the Magpies created hardly any at all from transition play (neither did Wolves, by the way). Instead, most of Newcastle's goals that weren't open play goals came from corners. Wigan were unusual in another way: they produced more goals from free kicks than the majority of other teams but were spectacularly ineffective at creating goals from corners.

There are lots of other differences and nuances we could point to: for example, some teams basically relied on open goals and corners - with a few other random goals thrown in: consider how similar Birmingham, Blackburn, Fulham, Newcastle, and Wolves look (some got more penalties, but that's it). I don't know if it's an accident that all of these teams had managers from the British Isles and/or Ireland, but the pattern did make me wonder about tactics and personnel.

Among the top teams, Manchester City looked the most like these teams (and obviously, their manager isn't English). In contrast, Manchester United and Chelsea were much more likely to mix their goal creation strategies, and were particularly effective at employing fast breaks.

Arsenal was different still, and perhaps the most unique (along with Wigan) among Premier League teams. The vast majority of their goals came from open play; they also led the league with 1.47 goals created per match from open play (in case you're wondering, Man United came in second at 1.44). On the flipside, Arsenal's levels of goal creation from situations other than open play looked more like Bolton's.

So, how did these patterns combine for each club to produce a profile of goal creation? For this, we can go back to the pie charts, which show the relative contribution of each match situation to creating goals for each club (in percentages). Take a look.

Open play goals were most important to Arsenal - no surprise at this point - but also Birmingham City. They were least important to teams like Blackpool, but also relatively less important to a whole host of clubs, ranging from Chelsea to Man City or Wigan (and others). The pie chart also reveals that lower quality teams generally relied more on corners (and free kicks to some extent) than the better teams (again, an exception is Manchester City). In contrast, teams like Chelsea, Everton, Manchester United, Sunderland, West Brom, and of course Wigan relied much more heavily on fast breaks to put the ball in the back of the net.

I'm sure there are details I'm overlooking, so feel free to let me know what you see and where I went off track. For my money, it seems clear that Wigan's goal creation strategy was the most unusual last year: they relied less on open play goals than most - they had 21 matches in which they failed to score a goal from open play last year. They also used fast breaks and free kicks more than anyone else. The numbers are remarkable; take a look at goal creation statistics for Wigan v. the league as a whole.

The numbers show that Wigan scored about 1/3 fewer goals from open play than the average EPL team, but twice as many from fast breaks; they managed 3.7 times as many goals from free kicks as other teams but only half as many goals from penalties; and they scored hardly any goals from corners at all.

I don't know Roberto Martinez, but I'd love to have a chat with him one of these days about how much of this was planned. But regardless, it seems to have done the trick.