Football's a simple game. If you score more or concede less than the other side, you win the match. So I thought it would be worth taking a look at which teams have been doing better than their opponents. The simplest way of doing just that is to calculate differentials for the stuff that matters most - goals - and the stuff without which the stuff that matters most usually doesn't happen (that would be shots, of course).
So, here, first of all are goal differentials by match, for the 20 Premier League clubs during the first 20 weeks of this season.
One thing that's immediately noticeable, regardless of name, is how few clubs consistently produce positive goal differentials. The season's top two (Manchester) teams clearly stand out, both for their consistency in producing positive goal differentials as well as the size of these differentials. But other trends are quite visible as well - compare, for example, Sunderland and Fulham. Sunderland's matches have been decided by just a goal for most of the season, while Fulham have had massive swings, it seems. Or compare Bolton and Blackburn, two clubs that are stuck in and around the relegation zone. Blackburn's consistent losses have been relatively small compared to Bolton's sizable (but also decreasing) defeats. Finally, Arsenal's terrible early season and recovery but weeks 10-12 show up very nicely, as does their subsequent decline.
Whatever you may read into these goal differentials, they're kind of fun to ponder, as are the following differentials on shots taken by each club in each match.
On shot differentials, things look quite different. Here, we see clearly that you don't actually have to outshoot your opponents or outshoot them by some margin to win the match. Take Manchester United, for example. Compared to their cross-town rivals City, United's goal differential looks much more modest. In fact, it looks more modest than that of several clubs, including Arsenal or Chelsea, and not all that different from, say, Everton. Speaking of the Toffees, one noticeable pattern about their shot differentials is that they are clearly able to create plenty of chances, and often more than their opponents. But this hasn't consistently translated into goals, a fate they have shared with fellow Merseysiders Liverpool FC so far this season. In contrast, some clubs have done reasonably well, even while consistently being outshot by their opponents. These include two promoted clubs (Swansea, Norwich), but also Newcastle. Whether the Swans and Canaries can continue to do this for the rest of the season and stay up, however, is a question well worth asking.
Finally, we can put shots and goals, along with points won, together in one graphic to see which clubs have consistently scored or won when outshooting their opponents. In the following graph, each dot is a match; their colors tell us whether the club won (green), drew (blue), or lost (red) that particular match. Take a look.
Interestingly, there aren't all that many clubs whose shot differential and goal differential have gone hand in hand very neatly. Swansea, Bolton, and Tottenham are among them - when they outshoot their opponents, they have been much more likely to take points. In contrast, Fulham, for example, are all over the place. And some clubs like Wigan or Wolves, have few dots in the upper right hand corner. Contrast that with Manchester City's pattern, for example - the one club with dots concentrated in the upper right of the box.
Surely, there are other patterns worth thinking about, but those will have to wait for another day.
