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The Daily Bee: Easing Your Mind with Numbers

Everyone is nervous about the final game of the season. Perhaps a more objective look at what’s in store will help?

Symbol image hacker Photo by Annette Riedl/picture alliance via Getty Images

Good Morning Fear the Wall

As we approach the final game of the season and the biggest game in recent memory for Borussia Dortmund, the Fear the Wall writers have had to come up with a different approach to the Daily Bee, simply because acting like this is a normal week isn’t going to cut it. Zac decided to stick to distraction, while Paddy ran headlong into the fire and focused only on the big weekend ahead. I thought I’d try a slightly different approach.

Zac mentioned in the introduction to Tuesday’s Daily Bee that he has seen a lot of “people being way too confident” about Saturday, and I thought I’d talk a little bit about the numbers behind the final act of this season’s thrilling title race. After all, the sport is played on a spreadsheet, so we should frame it in those terms.

League Probabilities

The first stop is to understand how some of the public sports analytics sites see the title race at this stage, and the good news is that they’re probably way more confident than any of us are! FiveThirtyEight gives BVB an 82% probability of winning the league versus Bayern’s 18%, while Opta’s The Analyst is slightly more confident about Dortmund’s chances, giving them an 85.9% probability of becoming Bundesliga champions.

These probabilities are driven by two main factors. First, the fact that BVB are the ones with the points advantage is the biggest driver for their significantly greater probability of winning the league. Second, the fact that BVB are at home on their final game of the season, while Bayern are away to Köln. Both sides are heavy favourites to win on Saturday, so the fact that the most likely outcomes for both leads to BVB coming away as champions is the reason that the probability is so heavily stacked in their favour, but Dortmund also have a slightly higher probability of winning their game (71%) than Bayern (62%), according to FiveThirtyEight.

Power Rankings

The part I find particularly interesting is considering how both sites rank Borussia Dortmund and Bayern Munich in their power rankings. Both FiveThirtyEight and The Analyst are quite confident that Bayern are, in reality, a better team than Dortmund. FiveThirtyEight gives Bayern a Soccer Power Index (SPI) rating of 88, and BVB an 83, while The Analyst gives Bayern a rating of 95.7 versus BVB’s 92.1. Although Bayern might still be a better team than BVB, when you look at the historical gap between the two team’s according to FiveThirtyEight, Dortmund are much closer to Bayern now than they have been at the start of any of the season’s that FiveThirtyEight makes available on their website.

It’s easy enough to see why Bayern are still ranked ahead of Dortmund. These rankings are influenced heavily by expected goals (xG), and Bayern’s xG Difference (xG For - xG Against) is significantly higher than Dortmund’s. I tend to agree with both the rankings, though I think the gap is probably even closer than either site sees it. The latest episode of the Double Pivot podcast took a little look at the Bundesliga title race, and they argued that what we’ve seen this season is not BVB surpassing Bayern as the better team, but that, for the first time in a long time, the gap is small enough that variance matters, and the variance has worked in Dortmund’s favour this time. I think that’s about right.

Betting Favourites

Finally, the bookies are often a good way to ground your expectations a little. They’re not perfect , but they’re still pretty solid.

SkyBet are confident that Borussia Dortmund are going to come away with the Meisterschale. They are giving BVB 1/8 odds of winning the Bundesliga title (versus Bayern’s 9/2), which translates to a probability of around 81%. So they’re slightly less confident than the public analytics sites, but I’d tend to favour those sites over the bookies because the bookies will also be adjusting their odds to try and bait you into spending money!

What Does All This Mean?

I think the conclusion we can take from this is that, in reality, BVB fans probably are not overconfident about this weekend. The probability of winning the league is over 80%, which is pretty good! I understand the sense of superstition, and I do think there’s a danger of being needlessly cocky about it, but I think fans should feel pretty good going into Saturday’s games.

That said, the probabilities do suggest that if we played the final game of the season infinitely many times, Bayern should come out as Bundesliga champions in around 20% of the time. That should give anyone that thinks this is in the bag some pause! Football is a high-variance sport and the margins between the two teams, with one game left, are extremely small. It’s very, very possible for Bayern to still win this, and as much as I think we’re right to feel confident, it’s important to recognise that there is a job to be done yet.

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Has my cold, calculated approach to processing the weekend’s permutations made you feel better or worse about the situation? Or are you just confused now?