It's no secret that footballers are creatures of habit.
John Terry used to occupy the exact same spot on the team bus before every away game for Chelsea, Laurent Blanc always kissed Fabian Barthez's bald head before a France match, and Borussia Dortmund defenders refuse to learn the lessons they're served week after week and continue to make the same mistakes.
At the top of the pitch, there is absolutely nothing wrong with Edin Terzic's side. In fact, aside from Bayern Munich, Dortmund boast the best attack in the Bundesliga with 50 goals in 24 matches. BVB have an abundance of creative talent, a determination, urgency, and bite in forward areas and a marksman who literally can't not score.
But at the other end of the field, nothing is going right. And nothing looks like changing.
It seemed as though Terzic had finally cracked the riddle of Dortmund's truly disastrous defensive woes when in February they went on a run of three clean sheets in good wins against Schalke, Arminia Bielefeld and Borussia Monchengladbach.
However, since then, BVB have been steamrolled by Bayern Munich in a 4-2 thumping and let a 2-0 lead slip to draw with Sevilla in the second leg of their Champions League round of 16 tie. Although the German side still qualified for the last eight, the two goals that clawed back the draw on the night brought up a recurring theme for those in black and yellow - a seemingly unescapable chaos that has hindered their whole season.
If Terzic's side don't eradicate their shoddy performances at the back, BVB may miss out on Champions League qualification this campaign, let alone silverware. So something desperately needs to change. But what?
Playing out from the back
One thing Dortmund have been guilty of is unnecessarily giving the ball away in dangerous positions.
A lack of urgency on the ball in their defensive third has given opposition the opportunity to press high and win the ball back time after time. The problem was exemplified on Tuesday night just two minutes into the game when Emre Can found Lucas Ocampos when attempting to sweep the ball out to Mateu Morey, leading to Marwin Hitz having to make a good save.
But Dortmund have proven that they're capable of adopting a more direct style with great effect. As seen above, the first goal against Bayern in the recent Der Klassiker came from a quick, measured pass into an advanced space, from which a high-pressing Thomas Delaney managed to win the second ball. Then, as you might expect, Erling Haaland did the rest. It goes to show that there is no need for BVB to put unnecessary pressure on themselves by forcing play at the back.
The second of Dortmund's two strikes against the Bavarians, however, displayed their capabilities in passing the ball quickly, effectively and ruthlessly on the ground. After a couple of passes the ball found its way to Thomas Meunier, whose brilliant switch to Nico Schulz set the move alight and the German found Thorgan Hazard to pull back for Haaland - 2-0, nine minutes gone, phenomenal.
The Norwegian's brace in Der Klassiker showed that Dortmund have options in getting the ball upfield. If they insist on playing out from the back, then it has to be spot on every time (like the second) but, if not, they can just as easily evade the opposition with a simple long ball and press to win the second battle (like the first).
Attitude and ability
Dortmund's defenders lack the commitment and edge that we see from their attacking colleagues.
Can has constantly let his side down with silly mistakes - for example, giving the penalty away against Sevilla with a push in the back that simply wasn't needed - and has never looked strong when attempting tackles in key areas of the pitch.
Meanwhile, Manuel Akanji is another who has rarely looked assured when featuring for BVB. The Swiss is first choice at the heart of defence along with Mats Hummels, but so often displays an astounding lack of awareness to lose markers and end up on the wrong side of his man in the box, inevitably leading to goals.
So many errors and goals this season could have been avoided with just that little bit more concentration and willingness to commit to the task. But these issues, unless rectified, will cost Dortmund points, qualification for the Champions League and ultimately trophies.
The transfer window has long since shut and the next opportunity to bring in talent will be once the season has reached its conclusion. But it is something that the club need to look at.
Hummels is now 32 years of age, and is the only top quality central defender available to Terzic. While Dan-Axel Zagadou is still only 21, the Frenchman looks prone to the same lapses in concentration as Akanji and Can and clearly needs more time to develop, making summer investment in defence crucial.
The type of player they will be able to acquire will depend on whether they achieve a top four Bundesliga finish.
But one thing is for sure; BVB's current defenders are not learning from their reckless errors and don't look as if they will. If that Dortmund back line don't change their chaotic nature, manager-to-be Marco Rose may look at a change in personnel instead of persisting with what he inherits - which may just be the answer.