A statistical argument that Borussia Dortmund are real contenders for the Champions League title.
Last season, Borussia Dortmund's run to the final of the Champions League was perhaps the best story in European football. A smaller club with a limited payroll that keeps ticket prices down and plays exciting high-tempo football, they checked basically all the boxes you could wish for as a neutral fan. Add in a visionary coach, revolutionary training regimes and Marco Reus' blonde flip, and you're looking at the total package. They very nearly toppled Bayern Munich in the final. They lost midfield ace Mario Götze to Bayern over the summer, but they have replaced him by increasing Reus' attacking responsibilities and blooding in Henrikh Mkhitaryan and the fantastically talented Pierre-Emerick Aubameyang.
Drawn into the most difficult group in the Champions League, Dortmund did what they needed to and finished first at 4-0-2. An 87th-minute game-winner at Stade Vélodrome by Kevin Großkreutz sealed first place and a meeting with Zenit St. Petersburg in the round of sixteen. This all sounds, doesn't it, like the story of a Champions League favorite? A great season, a smartly planned offseason, a gritty run through the group of death and a reasonable first-round draw.
But instead, BVB are about seventh in line for favorite status at the betting houses, with odds running as high as 20-to-1. Why is the world sleeping on Borussia Dortmund? It's pretty simple, I think. First, Dortmund's results in the Bundesliga this season have been only good. They've taken fewer than two points per match (42 from 22). If Dortmund aren't a great team in the Bundesliga, then they most likely aren't Champions League contenders. Second, Dortmund's struggles are attributable to a run of injuries the club has suffered. This isn't something random, but rather a real decline in quality due to missing a number of important pieces.
Advanced Statistics for Football
The first thing any case for Dortmund must do is explain their league form. Why spend all this time building up a third-place club? The reason is shots. In the 2013-2014 Bundesliga season, Borussia Dortmund have taken way more shots than they have allowed. Not only that, but the shots Dortmund have attempted have generally been played from much more favorable areas, assisted by easier types of passes, than the shots they have allowed.
Shots matter because shots, generally, are better predictors of future performance than goals. I have built a database of shots taken in the Bundesliga (as well as other leagues) to evaluate clubs based on the shots they take and allow. Obviously not all shots are created equal. Those shots taken from the center of the six-yard box are far more likely to be scored than shots from 30 yards. Shots assisted by through-balls are much more often scored than shots assisted by crosses. With this database, i can give every shot an expected goals value based on its location, shot type and the type of pass that assisted the shot. For more information, you can see the articles below, in particular the first three.
1) Expected Goals by Shot Location2) Crosses and Headers3) The Incredible Through-Ball4) Team Trends in Shot Quality5) Identifying Player Shooting Skill6) Player Shooting Data7) Stats For Managers: Spurs and Chelsea8) Atlético Madrid Shot Analysis9) Shot Differences Between European Leagues10) Shot and Pass Type Between European Leagues11) Barcelona's Tiki-Taka in the Stats
The basic upshot is that shots from the center of the 18-yard box, which I call the danger zone, are far better than shots from outside this area. To give a general sense of the values, shots from the danger zone are converted at a rate of about 1-in-6 (16.4%). Shots from wide areas in the box are converted at a rate of about 1-in-16 (6.1%) and shots from outside the box at a rate of about 1-in-30 (3.3%). Shots assisted by crosses are slightly more than half as likely to be goals as regular shots from the same areas, while shots assisted by through-balls are between 50% and twice as likely to be converted for goals as regular shots.
In the map on the right, I have the full shot matrix zones listed. Zones 1-3 comprise the danger zone, 4-5 are wide areas of the box and 6-8 are the zones outside the box.
Dortmund are fantastic at both creating shots within the danger zone and preventing the same from their opponents. Dortmund have taken 152 shots from the danger zone, second best in the Bundesliga behind Bayern of course, but over 30 shots more than third-place Hannover or fourth-place Leverkusen.
On the other side, BVB have allowed only 68 shots from the danger zone. This is again second to Bayern but 20 better than third-placed Leverkusen. The gap between Dortmund and Leverkusen, in the underlying stats, is significantly larger than the gap between Bayern and Dortmund.
These are the stats of a top, top side. I have been logging the shot statistics for the big four European leagues, and Dortmund's stats stack up with the best clubs in Europe.
Dortmund 2013-2014 by the Numbers
In the following charts, I compare Borussia Dortmund's underlying statistics in the league to those of the other clubs generally considered top contenders for the Champions League title. I have Bayern Munich as well from the Bundesliga, Real Madrid, Atlético Madrid and Barcelona from La Liga, and Chelsea from the Premier League. I'm looking at two different, highly important statistics. The first is Danger Zone Ratio, the rate of shots attempted from the danger zone to shots conceded from the danger zone. The second is Expected Goals Ratio, the rate of expected goals scored to expected goals conceded. Dortmund look like they below in this group, while Chelsea appear to fall a little bit short of the mark.
Dortmund have the numbers to match up with any of the top clubs. If they continue this pace of chance creation, they should be true competitors in the Champions League.
What about the injuries?
The other big problem for Dortmund, of course, has been missing players. They lost key defenders Neven Subotić and Mats Hummels to injury in November, and they have lost ground in the league since. Midfielders İlkay Gündoğan and Jakub Blaszczykowski are lost for the season, and several other key contributors have missed time. There's no easy way to map all the injuries, but I think drawing a line after Nov. 9, the last game together for Subotić and Hummels, makes sense enough. By my numbers, this has made a real difference. However, the difference has been mostly to bring Dortmund down to the rarefied level of a Champions League contender. In 12 league matches with Subotić and Hummels, Dortmund had an expected goals ratio of 0.76, the best in Europe. They have since dropped to about .66. Here are the stats pre- and post-injury for the central defenders, listed on a per-game basis.
%Cross and %TB refer to the percentage of shots from inside the danger zone assisted by crosses. Dortmund generally produce their shots through the middle (only ~30% of danger zone shots assisted by crossing), while forcing their opponents to create chances by riskier means.
| DZ Shots | W Shots | SoB | %Cross | %TB | xG | |
|---|---|---|---|---|---|---|
| Attack to Nov 9 | 7.5 | 4.6 | 8.3 | 36% | 9.1% | 2.4 |
| Attack Post Nov 9 | 6.2 | 3.3 | 4.8 | 24% | 4.8% | 1.8 |
| Defense to Nov 9 | 3.0 | 1.5 | 3.7 | 50% | 3.9% | 0.8 |
| Defense Post Nov 9 | 3.2 | 1.6 | 4.2 | 44% | 2.3% | 0.9 |
There's been real decline in the attacking and defending numbers. Especially the attacking stats. I'm not quite clear on what to do with that, since the injuries have hit the Dortmund back six much more heavily than their attacking front. In the matches I've watched -- admittedly a small sample -- it hasn't been my observation that Dortmund have sat men back particularly aggressively to cover for the injuries, though it would be a possible explanation. They do seem to be missing Gündoğan in midfield on the attacking side as much as the defensive. It's also possible that splitting a 22-match sample into two parts creates a lot of noise in the stats.
But let's take those numbers seriously. If Dortmund have lost their attacking edge and some of their defensive solidity, where do they stand among the European leaders? The following graph is the same as the first, but with Dortmund's numbers limited only to post-Nov. 9th.
Even in their reduced form since November, Dortmund have the underlying stats of a capable Champions League contender. They fall back a bit, but not by so much that you'd see BVB as an afterthought in the last sixteen. I may look stupid by the end of the day on Tuesday, but Borussia Dortmund look to me like a club with a legitimate shot at winning the Champions League.